[7/7] devfreq: move statistics to separate struct

Commit Message

Kamil Konieczny Nov. 13, 2019, 9:13 a.m. UTC

Count time and transitions between devfreq frequencies in separate struct
for improved code readability and maintenance.

Signed-off-by: Kamil Konieczny <[e-mail]>
---
 drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
 drivers/devfreq/exynos-bus.c       |   6 +-
 drivers/devfreq/governor_passive.c |  26 +++--
 include/linux/devfreq.h            |  43 ++++----
 4 files changed, 129 insertions(+), 102 deletions(-)

Comments

Chanwoo Choi Nov. 14, 2019, 1:52 a.m. UTC | #1

Hi Kamil,

The 'freq_table' and 'max_state' in the devfreq_dev_profile
were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
device driver was posted to mainline kernel, they used
them for a long time. It means that this patch break
the compatibility. The ARM Mali drivers are very
important devfreq device driver. 

[1] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
[2] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
[3] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel

Also, the devfreq device driver specifies their own
information and data into devfreq_dev_profile structure 
before registering the devfreq device with devfreq_add_device().
This patch breaks the basic usage rule of devfreq_dev_profile structure.

So, I can't agree this patch. Not ack.

Regards,
Chanwoo Choi

On 11/13/19 6:13 PM, Kamil Konieczny wrote:
> Count time and transitions between devfreq frequencies in separate struct
> for improved code readability and maintenance.
> 
> Signed-off-by: Kamil Konieczny <[e-mail]>
> ---
>  drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>  drivers/devfreq/exynos-bus.c       |   6 +-
>  drivers/devfreq/governor_passive.c |  26 +++--
>  include/linux/devfreq.h            |  43 ++++----
>  4 files changed, 129 insertions(+), 102 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index d79412b0de59..d85867a91230 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>   */
>  static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>  {
> +	struct devfreq_stats *stats = devfreq->profile->stats;
>  	int lev;
>  
> -	for (lev = 0; lev < devfreq->profile->max_state; lev++)
> -		if (freq == devfreq->profile->freq_table[lev])
> +	for (lev = 0; lev < stats->max_state; lev++)
> +		if (freq == stats->freq_table[lev])
>  			return lev;
>  
>  	return -EINVAL;
> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>  static int set_freq_table(struct devfreq *devfreq)
>  {
>  	struct devfreq_dev_profile *profile = devfreq->profile;
> +	struct devfreq_stats *stats;
>  	struct dev_pm_opp *opp;
>  	unsigned long freq;
> -	int i, count;
> +	int i, count, err = -ENOMEM;
>  
>  	/* Initialize the freq_table from OPP table */
>  	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>  	if (count <= 0)
>  		return -EINVAL;
>  
> -	profile->max_state = count;
> -	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
> -					count,
> -					sizeof(*profile->freq_table),
> -					GFP_KERNEL);
> -	if (!profile->freq_table) {
> -		profile->max_state = 0;
> +	stats = devm_kzalloc(devfreq->dev.parent,
> +			     sizeof(struct devfreq_stats), GFP_KERNEL);
> +	if (!stats)
>  		return -ENOMEM;
> -	}
>  
> -	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
> +	profile->stats = stats;
> +	stats->max_state = count;
> +	stats->freq_table = devm_kcalloc(devfreq->dev.parent,
> +					 count,
> +					 sizeof(*stats->freq_table),
> +					 GFP_KERNEL);
> +	if (!stats->freq_table)
> +		goto err_no_mem;
> +
> +	for (i = 0, freq = 0; i < count; i++, freq++) {
>  		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>  		if (IS_ERR(opp)) {
> -			devm_kfree(devfreq->dev.parent, profile->freq_table);
> -			profile->max_state = 0;
> -			return PTR_ERR(opp);
> +			devm_kfree(devfreq->dev.parent, stats->freq_table);
> +			stats->max_state = 0;
> +			err = PTR_ERR(opp);
> +			goto err_no_mem;
>  		}
>  		dev_pm_opp_put(opp);
> -		profile->freq_table[i] = freq;
> +		stats->freq_table[i] = freq;
>  	}
>  
> -	profile->trans_table = devm_kzalloc(devfreq->dev.parent,
> -					    array3_size(sizeof(unsigned int),
> -							count, count),
> -					    GFP_KERNEL);
> -	if (!profile->trans_table)
> +	stats->trans_table = devm_kzalloc(devfreq->dev.parent,
> +					  array3_size(sizeof(unsigned int),
> +						      count, count),
> +					  GFP_KERNEL);
> +	if (!stats->trans_table)
>  		goto err_no_mem;
>  
> -	profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
> -					      sizeof(*profile->time_in_state),
> -					      GFP_KERNEL);
> -	if (!profile->time_in_state)
> +	stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
> +					    sizeof(*stats->time_in_state),
> +					    GFP_KERNEL);
> +	if (!stats->time_in_state)
>  		goto err_no_mem;
>  
> -	profile->last_time = get_jiffies_64();
> -	spin_lock_init(&profile->stats_lock);
> +	stats->last_time = get_jiffies_64();
> +	spin_lock_init(&stats->stats_lock);
>  
>  	return 0;
>  err_no_mem:
> -	profile->max_state = 0;
> -	return -ENOMEM;
> +	stats->max_state = 0;
> +	devm_kfree(devfreq->dev.parent, profile->stats);
> +	profile->stats = NULL;
> +	return err;
>  }
>  
>  /**
> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>   */
>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  {
> -	struct devfreq_dev_profile *profile = devfreq->profile;
> +	struct devfreq_stats *stats = devfreq->profile->stats;
>  	unsigned long long cur_time;
>  	int lev, prev_lev, ret = 0;
>  
> @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  
>  	/* Immediately exit if previous_freq is not initialized yet. */
>  	if (!devfreq->previous_freq) {
> -		spin_lock(&profile->stats_lock);
> -		profile->last_time = cur_time;
> -		spin_unlock(&profile->stats_lock);
> +		spin_lock(&stats->stats_lock);
> +		stats->last_time = cur_time;
> +		spin_unlock(&stats->stats_lock);
>  		return 0;
>  	}
>  
>  	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>  
> -	spin_lock(&profile->stats_lock);
> +	spin_lock(&stats->stats_lock);
>  	if (prev_lev < 0) {
>  		ret = prev_lev;
>  		goto out;
>  	}
>  
> -	profile->time_in_state[prev_lev] +=
> -			 cur_time - profile->last_time;
> +	stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>  	lev = devfreq_get_freq_level(devfreq, freq);
>  	if (lev < 0) {
>  		ret = lev;
> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  	}
>  
>  	if (lev != prev_lev) {
> -		profile->trans_table[(prev_lev *
> -				profile->max_state) + lev]++;
> -		profile->total_trans++;
> +		stats->trans_table[(prev_lev *
> +				stats->max_state) + lev]++;
> +		stats->total_trans++;
>  	}
>  
>  out:
> -	profile->last_time = cur_time;
> -	spin_unlock(&profile->stats_lock);
> +	stats->last_time = cur_time;
> +	spin_unlock(&stats->stats_lock);
>  	return ret;
>  }
>  EXPORT_SYMBOL(devfreq_update_status);
> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>  		queue_delayed_work(devfreq_wq, &devfreq->work,
>  			msecs_to_jiffies(profile->polling_ms));
>  
> -	spin_lock(&profile->stats_lock);
> -	profile->last_time = get_jiffies_64();
> -	spin_unlock(&profile->stats_lock);
> +	spin_lock(&profile->stats->stats_lock);
> +	profile->stats->last_time = get_jiffies_64();
> +	spin_unlock(&profile->stats->stats_lock);
>  	devfreq->stop_polling = false;
>  
>  	if (profile->get_cur_freq &&
> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  	devfreq->data = data;
>  	devfreq->nb.notifier_call = devfreq_notifier_call;
>  
> -	if (!profile->max_state && !profile->freq_table) {
> +	if (!profile->stats) {
>  		mutex_unlock(&devfreq->lock);
>  		err = set_freq_table(devfreq);
>  		if (err < 0)
> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>  			      const char *buf, size_t count)
>  {
>  	struct devfreq *df = to_devfreq(dev);
> +	struct devfreq_stats *stats = df->profile->stats;
>  	unsigned long value;
>  	int ret;
>  
> @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>  			goto unlock;
>  		}
>  	} else {
> -		unsigned long *freq_table = df->profile->freq_table;
> +		unsigned long *freq_table = stats->freq_table;
>  
>  		/* Get minimum frequency according to sorting order */
> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>  			value = freq_table[0];
>  		else
> -			value = freq_table[df->profile->max_state - 1];
> +			value = freq_table[stats->max_state - 1];
>  	}
>  
>  	df->min_freq = value;
> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>  			      const char *buf, size_t count)
>  {
>  	struct devfreq *df = to_devfreq(dev);
> +	struct devfreq_stats *stats = df->profile->stats;
>  	unsigned long value;
>  	int ret;
>  
> @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>  			goto unlock;
>  		}
>  	} else {
> -		unsigned long *freq_table = df->profile->freq_table;
> +		unsigned long *freq_table = stats->freq_table;
>  
>  		/* Get maximum frequency according to sorting order */
> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
> -			value = freq_table[df->profile->max_state - 1];
> +		if (freq_table[0] < freq_table[stats->max_state - 1])
> +			value = freq_table[stats->max_state - 1];
>  		else
>  			value = freq_table[0];
>  	}
> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>  					  char *buf)
>  {
>  	struct devfreq *df = to_devfreq(d);
> +	struct devfreq_stats *stats = df->profile->stats;
>  	ssize_t count = 0;
>  	int i;
>  
>  	mutex_lock(&df->lock);
>  
> -	for (i = 0; i < df->profile->max_state; i++)
> +	for (i = 0; i < stats->max_state; i++)
>  		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
> -				"%lu ", df->profile->freq_table[i]);
> +				"%lu ", stats->freq_table[i]);
>  
>  	mutex_unlock(&df->lock);
>  	/* Truncate the trailing space */
> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>  {
>  	struct devfreq *devfreq = to_devfreq(dev);
>  	struct devfreq_dev_profile *profile = devfreq->profile;
> +	struct devfreq_stats *stats = profile->stats;
> +	unsigned int max_state = stats->max_state;
>  	ssize_t len;
>  	int i, j;
> -	unsigned int max_state = profile->max_state;
>  
>  	if (!devfreq->stop_polling &&
>  			devfreq_update_status(devfreq, devfreq->previous_freq))
> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>  	len = sprintf(buf, "     From  :   To\n");
>  	len += sprintf(buf + len, "           :");
>  
> -	spin_lock(&profile->stats_lock);
> +	spin_lock(&stats->stats_lock);
>  	for (i = 0; i < max_state; i++)
>  		len += sprintf(buf + len, "%10lu",
> -				profile->freq_table[i]);
> +				stats->freq_table[i]);
>  
>  	len += sprintf(buf + len, "   time(ms)\n");
>  
>  	for (i = 0; i < max_state; i++) {
> -		if (profile->freq_table[i] == devfreq->previous_freq)
> +		if (stats->freq_table[i] == devfreq->previous_freq)
>  			len += sprintf(buf + len, "*");
>  		else
>  			len += sprintf(buf + len, " ");
>  
>  		len += sprintf(buf + len, "%10lu:",
> -				profile->freq_table[i]);
> +				stats->freq_table[i]);
>  		for (j = 0; j < max_state; j++)
>  			len += sprintf(buf + len, "%10u",
> -				profile->trans_table[(i * max_state) + j]);
> +				stats->trans_table[(i * max_state) + j]);
>  		len += sprintf(buf + len, "%10llu\n", (u64)
> -			jiffies64_to_msecs(profile->time_in_state[i]));
> +			jiffies64_to_msecs(stats->time_in_state[i]));
>  	}
>  
>  	len += sprintf(buf + len, "Total transition : %u\n",
> -					profile->total_trans);
> -	spin_unlock(&profile->stats_lock);
> +					stats->total_trans);
> +	spin_unlock(&stats->stats_lock);
>  	return len;
>  }
>  static DEVICE_ATTR_RO(trans_stat);
>  
> -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>  {
> -	unsigned int count = profile->max_state;
> -
> -	spin_lock(&profile->stats_lock);
> -	memset(profile->time_in_state, 0, count * sizeof(u64));
> -	memset(profile->trans_table, 0, count * count * sizeof(int));
> -	profile->last_time = get_jiffies_64();
> -	profile->total_trans = 0;
> -	spin_unlock(&profile->stats_lock);
> +	unsigned int count = stats->max_state;
> +
> +	spin_lock(&stats->stats_lock);
> +	memset(stats->time_in_state, 0, count * sizeof(u64));
> +	memset(stats->trans_table, 0, count * count * sizeof(int));
> +	stats->last_time = get_jiffies_64();
> +	stats->total_trans = 0;
> +	spin_unlock(&stats->stats_lock);
>  }
>  
>  static ssize_t trans_reset_store(struct device *dev,
> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>  {
>  	struct devfreq *devfreq = to_devfreq(dev);
>  
> -	defvreq_stats_clear_table(devfreq->profile);
> +	defvreq_stats_clear_table(devfreq->profile->stats);
>  
>  	return count;
>  }
> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
> index d9f377912c10..b212aae2bb3e 100644
> --- a/drivers/devfreq/exynos-bus.c
> +++ b/drivers/devfreq/exynos-bus.c
> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>  	}
>  
>  out:
> -	max_state = bus->devfreq->profile->max_state;
> -	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
> -	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
> +	max_state = profile->stats->max_state;
> +	min_freq = (profile->stats->freq_table[0] / 1000);
> +	max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>  	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>  			dev_name(dev), min_freq, max_freq);
>  
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 58308948b863..b2d87a88335c 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  	struct devfreq_passive_data *p_data
>  			= (struct devfreq_passive_data *)devfreq->data;
>  	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
> +	struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
> +	struct devfreq_stats *stats;
>  	unsigned long child_freq = ULONG_MAX;
>  	struct dev_pm_opp *opp;
>  	int i, count, ret = 0;
> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  	 * device. And then the index is used for getting the suitable
>  	 * new frequency for passive devfreq device.
>  	 */
> -	if (!devfreq->profile || !devfreq->profile->freq_table
> -		|| devfreq->profile->max_state <= 0)
> +	if (!devfreq->profile || !devfreq->profile->stats ||
> +	    devfreq->profile->stats->max_state <= 0 ||
> +	    !parent_devfreq->profile ||	!parent_devfreq->profile->stats ||
> +	    parent_devfreq->profile->stats->max_state <= 0)
>  		return -EINVAL;
>  
> +	stats = devfreq->profile->stats;
> +	parent_stats = parent_devfreq->profile->stats;
>  	/*
>  	 * The passive governor have to get the correct frequency from OPP
>  	 * list of parent device. Because in this case, *freq is temporary
> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  	 * Get the OPP table's index of decided freqeuncy by governor
>  	 * of parent device.
>  	 */
> -	for (i = 0; i < parent_devfreq->profile->max_state; i++)
> -		if (parent_devfreq->profile->freq_table[i] == *freq)
> +	for (i = 0; i < parent_stats->max_state; i++)
> +		if (parent_stats->freq_table[i] == *freq)
>  			break;
>  
> -	if (i == parent_devfreq->profile->max_state) {
> +	if (i == parent_stats->max_state) {
>  		ret = -EINVAL;
>  		goto out;
>  	}
>  
>  	/* Get the suitable frequency by using index of parent device. */
> -	if (i < devfreq->profile->max_state) {
> -		child_freq = devfreq->profile->freq_table[i];
> +	if (i < stats->max_state) {
> +		child_freq = stats->freq_table[i];
>  	} else {
> -		count = devfreq->profile->max_state;
> -		child_freq = devfreq->profile->freq_table[count - 1];
> +		count = stats->max_state;
> +		child_freq = stats->freq_table[count - 1];
>  	}
>  
>  	/* Return the suitable frequency for passive device. */
> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>  	if (ret < 0)
>  		goto out;
>  
> -	if (devfreq->profile->freq_table
> +	if (devfreq->profile->stats
>  		&& (devfreq_update_status(devfreq, freq)))
>  		dev_err(&devfreq->dev,
>  			"Couldn't update frequency transition information.\n");
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 4ceb2a517a9c..8459af1a1583 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>   */
>  #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1
>  
> +/**
> + * struct devfreq_stats - Devfreq's transitions stats counters
> + * @freq_table:		Optional list of frequencies to support statistics
> + *			and freq_table must be generated in ascending order.
> + * @max_state:		The size of freq_table.
> + * @total_trans:	Number of devfreq transitions
> + * @trans_table:	Statistics of devfreq transitions
> + * @time_in_state:	Statistics of devfreq states
> + * @last_time:		The last time stats were updated
> + * @stats_lock:		Lock protecting trans_table, time_in_state,
> + *			last_time and total_trans used for statistics
> + */
> +struct devfreq_stats {
> +	unsigned long *freq_table;
> +	unsigned int max_state;
> +
> +	/* information for device frequency transition */
> +	unsigned int total_trans;
> +	unsigned int *trans_table;
> +	u64 *time_in_state;
> +	unsigned long long last_time;
> +	spinlock_t stats_lock;
> +};
> +
>  /**
>   * struct devfreq_dev_profile - Devfreq's user device profile
>   * @initial_freq:	The operating frequency when devfreq_add_device() is
> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>   *			from devfreq_remove_device() call. If the user
>   *			has registered devfreq->nb at a notifier-head,
>   *			this is the time to unregister it.
> - * @freq_table:		Optional list of frequencies to support statistics
> - *			and freq_table must be generated in ascending order.
> - * @max_state:		The size of freq_table.
> - * @total_trans:	Number of devfreq transitions
> - * @trans_table:	Statistics of devfreq transitions
> - * @time_in_state:	Statistics of devfreq states
> - * @last_time:		The last time stats were updated
> - * @stats_lock:		Lock protecting trans_table, time_in_state,
> - *			last_time and total_trans used for statistics
> + * @stats:		Statistics of devfreq states and state transitions
>   */
>  struct devfreq_dev_profile {
>  	unsigned long initial_freq;
> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>  	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>  	void (*exit)(struct device *dev);
>  
> -	unsigned long *freq_table;
> -	unsigned int max_state;
> -	/* information for device frequency transition */
> -	unsigned int total_trans;
> -	unsigned int *trans_table;
> -	u64 *time_in_state;
> -	unsigned long long last_time;
> -	spinlock_t stats_lock;
> +	struct devfreq_stats *stats;
>  };
>  
>  /**
>

Bartlomiej Zolnierkiewicz Nov. 14, 2019, 6:01 p.m. UTC | #2

Hi Chanwoo,

On 11/14/19 2:52 AM, Chanwoo Choi wrote:
> Hi Kamil,
> 
> The 'freq_table' and 'max_state' in the devfreq_dev_profile
> were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
> device driver was posted to mainline kernel, they used
> them for a long time. It means that this patch break
> the compatibility. The ARM Mali drivers are very
> important devfreq device driver. 

This argument is not a a technical one and the official upstream
kernel policy is to not depend on out-of-tree drivers.

Besides the ARM Mali drivers are full of code like:

#if LINUX_VERSION_CODE >= KERNEL_VERSION(x, y, z)
...
#else
...
#endif

so few more instances of similar code won't do any harm.. ;-)

> [1] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
> [2] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
> [3] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel

I took a look at ARM Mali drivers source code anyway and I fail to
see a rationale behind their behavior of doing 'freq_table' and
'max_state' initialization in the driver itself (instead of leaving
it up to the devfreq core code, like all in-kernel drivers are doing
already).

Could you please explain rationale behind ARM Mali drivers' special
needs?

[ Both ARM Mali and devfreq core code are using generic PM OPP code
  these days to do 'freq_table' and 'max_state' initialization, the
  only difference seems to be that ARM Mali creates the frequency
  table in the descending order (but there also seems to be no real
  need for it). ]

Maybe this is an opportunity to simplify also the ARM Mali driver?

> Also, the devfreq device driver specifies their own
> information and data into devfreq_dev_profile structure 
> before registering the devfreq device with devfreq_add_device().
> This patch breaks the basic usage rule of devfreq_dev_profile structure.

Well, 'struct devfreq_stats *stats' can be trivially moved out of
'struct devfreq_profile' to 'struct devfreq' if you prefer it that
way..

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> So, I can't agree this patch. Not ack.
> 
> Regards,
> Chanwoo Choi
> 
> On 11/13/19 6:13 PM, Kamil Konieczny wrote:
>> Count time and transitions between devfreq frequencies in separate struct
>> for improved code readability and maintenance.
>>
>> Signed-off-by: Kamil Konieczny <[e-mail]>
>> ---
>>  drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>>  drivers/devfreq/exynos-bus.c       |   6 +-
>>  drivers/devfreq/governor_passive.c |  26 +++--
>>  include/linux/devfreq.h            |  43 ++++----
>>  4 files changed, 129 insertions(+), 102 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index d79412b0de59..d85867a91230 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>   */
>>  static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>  {
>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>  	int lev;
>>  
>> -	for (lev = 0; lev < devfreq->profile->max_state; lev++)
>> -		if (freq == devfreq->profile->freq_table[lev])
>> +	for (lev = 0; lev < stats->max_state; lev++)
>> +		if (freq == stats->freq_table[lev])
>>  			return lev;
>>  
>>  	return -EINVAL;
>> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>  static int set_freq_table(struct devfreq *devfreq)
>>  {
>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>> +	struct devfreq_stats *stats;
>>  	struct dev_pm_opp *opp;
>>  	unsigned long freq;
>> -	int i, count;
>> +	int i, count, err = -ENOMEM;
>>  
>>  	/* Initialize the freq_table from OPP table */
>>  	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>>  	if (count <= 0)
>>  		return -EINVAL;
>>  
>> -	profile->max_state = count;
>> -	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
>> -					count,
>> -					sizeof(*profile->freq_table),
>> -					GFP_KERNEL);
>> -	if (!profile->freq_table) {
>> -		profile->max_state = 0;
>> +	stats = devm_kzalloc(devfreq->dev.parent,
>> +			     sizeof(struct devfreq_stats), GFP_KERNEL);
>> +	if (!stats)
>>  		return -ENOMEM;
>> -	}
>>  
>> -	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
>> +	profile->stats = stats;
>> +	stats->max_state = count;
>> +	stats->freq_table = devm_kcalloc(devfreq->dev.parent,
>> +					 count,
>> +					 sizeof(*stats->freq_table),
>> +					 GFP_KERNEL);
>> +	if (!stats->freq_table)
>> +		goto err_no_mem;
>> +
>> +	for (i = 0, freq = 0; i < count; i++, freq++) {
>>  		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>>  		if (IS_ERR(opp)) {
>> -			devm_kfree(devfreq->dev.parent, profile->freq_table);
>> -			profile->max_state = 0;
>> -			return PTR_ERR(opp);
>> +			devm_kfree(devfreq->dev.parent, stats->freq_table);
>> +			stats->max_state = 0;
>> +			err = PTR_ERR(opp);
>> +			goto err_no_mem;
>>  		}
>>  		dev_pm_opp_put(opp);
>> -		profile->freq_table[i] = freq;
>> +		stats->freq_table[i] = freq;
>>  	}
>>  
>> -	profile->trans_table = devm_kzalloc(devfreq->dev.parent,
>> -					    array3_size(sizeof(unsigned int),
>> -							count, count),
>> -					    GFP_KERNEL);
>> -	if (!profile->trans_table)
>> +	stats->trans_table = devm_kzalloc(devfreq->dev.parent,
>> +					  array3_size(sizeof(unsigned int),
>> +						      count, count),
>> +					  GFP_KERNEL);
>> +	if (!stats->trans_table)
>>  		goto err_no_mem;
>>  
>> -	profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>> -					      sizeof(*profile->time_in_state),
>> -					      GFP_KERNEL);
>> -	if (!profile->time_in_state)
>> +	stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>> +					    sizeof(*stats->time_in_state),
>> +					    GFP_KERNEL);
>> +	if (!stats->time_in_state)
>>  		goto err_no_mem;
>>  
>> -	profile->last_time = get_jiffies_64();
>> -	spin_lock_init(&profile->stats_lock);
>> +	stats->last_time = get_jiffies_64();
>> +	spin_lock_init(&stats->stats_lock);
>>  
>>  	return 0;
>>  err_no_mem:
>> -	profile->max_state = 0;
>> -	return -ENOMEM;
>> +	stats->max_state = 0;
>> +	devm_kfree(devfreq->dev.parent, profile->stats);
>> +	profile->stats = NULL;
>> +	return err;
>>  }
>>  
>>  /**
>> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>   */
>>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  {
>> -	struct devfreq_dev_profile *profile = devfreq->profile;
>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>  	unsigned long long cur_time;
>>  	int lev, prev_lev, ret = 0;
>>  
>> @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  
>>  	/* Immediately exit if previous_freq is not initialized yet. */
>>  	if (!devfreq->previous_freq) {
>> -		spin_lock(&profile->stats_lock);
>> -		profile->last_time = cur_time;
>> -		spin_unlock(&profile->stats_lock);
>> +		spin_lock(&stats->stats_lock);
>> +		stats->last_time = cur_time;
>> +		spin_unlock(&stats->stats_lock);
>>  		return 0;
>>  	}
>>  
>>  	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>>  
>> -	spin_lock(&profile->stats_lock);
>> +	spin_lock(&stats->stats_lock);
>>  	if (prev_lev < 0) {
>>  		ret = prev_lev;
>>  		goto out;
>>  	}
>>  
>> -	profile->time_in_state[prev_lev] +=
>> -			 cur_time - profile->last_time;
>> +	stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>>  	lev = devfreq_get_freq_level(devfreq, freq);
>>  	if (lev < 0) {
>>  		ret = lev;
>> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  	}
>>  
>>  	if (lev != prev_lev) {
>> -		profile->trans_table[(prev_lev *
>> -				profile->max_state) + lev]++;
>> -		profile->total_trans++;
>> +		stats->trans_table[(prev_lev *
>> +				stats->max_state) + lev]++;
>> +		stats->total_trans++;
>>  	}
>>  
>>  out:
>> -	profile->last_time = cur_time;
>> -	spin_unlock(&profile->stats_lock);
>> +	stats->last_time = cur_time;
>> +	spin_unlock(&stats->stats_lock);
>>  	return ret;
>>  }
>>  EXPORT_SYMBOL(devfreq_update_status);
>> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>  		queue_delayed_work(devfreq_wq, &devfreq->work,
>>  			msecs_to_jiffies(profile->polling_ms));
>>  
>> -	spin_lock(&profile->stats_lock);
>> -	profile->last_time = get_jiffies_64();
>> -	spin_unlock(&profile->stats_lock);
>> +	spin_lock(&profile->stats->stats_lock);
>> +	profile->stats->last_time = get_jiffies_64();
>> +	spin_unlock(&profile->stats->stats_lock);
>>  	devfreq->stop_polling = false;
>>  
>>  	if (profile->get_cur_freq &&
>> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  	devfreq->data = data;
>>  	devfreq->nb.notifier_call = devfreq_notifier_call;
>>  
>> -	if (!profile->max_state && !profile->freq_table) {
>> +	if (!profile->stats) {
>>  		mutex_unlock(&devfreq->lock);
>>  		err = set_freq_table(devfreq);
>>  		if (err < 0)
>> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>  			      const char *buf, size_t count)
>>  {
>>  	struct devfreq *df = to_devfreq(dev);
>> +	struct devfreq_stats *stats = df->profile->stats;
>>  	unsigned long value;
>>  	int ret;
>>  
>> @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>  			goto unlock;
>>  		}
>>  	} else {
>> -		unsigned long *freq_table = df->profile->freq_table;
>> +		unsigned long *freq_table = stats->freq_table;
>>  
>>  		/* Get minimum frequency according to sorting order */
>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>  			value = freq_table[0];
>>  		else
>> -			value = freq_table[df->profile->max_state - 1];
>> +			value = freq_table[stats->max_state - 1];
>>  	}
>>  
>>  	df->min_freq = value;
>> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>  			      const char *buf, size_t count)
>>  {
>>  	struct devfreq *df = to_devfreq(dev);
>> +	struct devfreq_stats *stats = df->profile->stats;
>>  	unsigned long value;
>>  	int ret;
>>  
>> @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>  			goto unlock;
>>  		}
>>  	} else {
>> -		unsigned long *freq_table = df->profile->freq_table;
>> +		unsigned long *freq_table = stats->freq_table;
>>  
>>  		/* Get maximum frequency according to sorting order */
>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>> -			value = freq_table[df->profile->max_state - 1];
>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>> +			value = freq_table[stats->max_state - 1];
>>  		else
>>  			value = freq_table[0];
>>  	}
>> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>>  					  char *buf)
>>  {
>>  	struct devfreq *df = to_devfreq(d);
>> +	struct devfreq_stats *stats = df->profile->stats;
>>  	ssize_t count = 0;
>>  	int i;
>>  
>>  	mutex_lock(&df->lock);
>>  
>> -	for (i = 0; i < df->profile->max_state; i++)
>> +	for (i = 0; i < stats->max_state; i++)
>>  		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
>> -				"%lu ", df->profile->freq_table[i]);
>> +				"%lu ", stats->freq_table[i]);
>>  
>>  	mutex_unlock(&df->lock);
>>  	/* Truncate the trailing space */
>> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>  {
>>  	struct devfreq *devfreq = to_devfreq(dev);
>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>> +	struct devfreq_stats *stats = profile->stats;
>> +	unsigned int max_state = stats->max_state;
>>  	ssize_t len;
>>  	int i, j;
>> -	unsigned int max_state = profile->max_state;
>>  
>>  	if (!devfreq->stop_polling &&
>>  			devfreq_update_status(devfreq, devfreq->previous_freq))
>> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>>  	len = sprintf(buf, "     From  :   To\n");
>>  	len += sprintf(buf + len, "           :");
>>  
>> -	spin_lock(&profile->stats_lock);
>> +	spin_lock(&stats->stats_lock);
>>  	for (i = 0; i < max_state; i++)
>>  		len += sprintf(buf + len, "%10lu",
>> -				profile->freq_table[i]);
>> +				stats->freq_table[i]);
>>  
>>  	len += sprintf(buf + len, "   time(ms)\n");
>>  
>>  	for (i = 0; i < max_state; i++) {
>> -		if (profile->freq_table[i] == devfreq->previous_freq)
>> +		if (stats->freq_table[i] == devfreq->previous_freq)
>>  			len += sprintf(buf + len, "*");
>>  		else
>>  			len += sprintf(buf + len, " ");
>>  
>>  		len += sprintf(buf + len, "%10lu:",
>> -				profile->freq_table[i]);
>> +				stats->freq_table[i]);
>>  		for (j = 0; j < max_state; j++)
>>  			len += sprintf(buf + len, "%10u",
>> -				profile->trans_table[(i * max_state) + j]);
>> +				stats->trans_table[(i * max_state) + j]);
>>  		len += sprintf(buf + len, "%10llu\n", (u64)
>> -			jiffies64_to_msecs(profile->time_in_state[i]));
>> +			jiffies64_to_msecs(stats->time_in_state[i]));
>>  	}
>>  
>>  	len += sprintf(buf + len, "Total transition : %u\n",
>> -					profile->total_trans);
>> -	spin_unlock(&profile->stats_lock);
>> +					stats->total_trans);
>> +	spin_unlock(&stats->stats_lock);
>>  	return len;
>>  }
>>  static DEVICE_ATTR_RO(trans_stat);
>>  
>> -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
>> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>>  {
>> -	unsigned int count = profile->max_state;
>> -
>> -	spin_lock(&profile->stats_lock);
>> -	memset(profile->time_in_state, 0, count * sizeof(u64));
>> -	memset(profile->trans_table, 0, count * count * sizeof(int));
>> -	profile->last_time = get_jiffies_64();
>> -	profile->total_trans = 0;
>> -	spin_unlock(&profile->stats_lock);
>> +	unsigned int count = stats->max_state;
>> +
>> +	spin_lock(&stats->stats_lock);
>> +	memset(stats->time_in_state, 0, count * sizeof(u64));
>> +	memset(stats->trans_table, 0, count * count * sizeof(int));
>> +	stats->last_time = get_jiffies_64();
>> +	stats->total_trans = 0;
>> +	spin_unlock(&stats->stats_lock);
>>  }
>>  
>>  static ssize_t trans_reset_store(struct device *dev,
>> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>>  {
>>  	struct devfreq *devfreq = to_devfreq(dev);
>>  
>> -	defvreq_stats_clear_table(devfreq->profile);
>> +	defvreq_stats_clear_table(devfreq->profile->stats);
>>  
>>  	return count;
>>  }
>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>> index d9f377912c10..b212aae2bb3e 100644
>> --- a/drivers/devfreq/exynos-bus.c
>> +++ b/drivers/devfreq/exynos-bus.c
>> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>  	}
>>  
>>  out:
>> -	max_state = bus->devfreq->profile->max_state;
>> -	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>> -	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>> +	max_state = profile->stats->max_state;
>> +	min_freq = (profile->stats->freq_table[0] / 1000);
>> +	max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>>  	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>>  			dev_name(dev), min_freq, max_freq);
>>  
>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>> index 58308948b863..b2d87a88335c 100644
>> --- a/drivers/devfreq/governor_passive.c
>> +++ b/drivers/devfreq/governor_passive.c
>> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>  	struct devfreq_passive_data *p_data
>>  			= (struct devfreq_passive_data *)devfreq->data;
>>  	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>> +	struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
>> +	struct devfreq_stats *stats;
>>  	unsigned long child_freq = ULONG_MAX;
>>  	struct dev_pm_opp *opp;
>>  	int i, count, ret = 0;
>> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>  	 * device. And then the index is used for getting the suitable
>>  	 * new frequency for passive devfreq device.
>>  	 */
>> -	if (!devfreq->profile || !devfreq->profile->freq_table
>> -		|| devfreq->profile->max_state <= 0)
>> +	if (!devfreq->profile || !devfreq->profile->stats ||
>> +	    devfreq->profile->stats->max_state <= 0 ||
>> +	    !parent_devfreq->profile ||	!parent_devfreq->profile->stats ||
>> +	    parent_devfreq->profile->stats->max_state <= 0)
>>  		return -EINVAL;
>>  
>> +	stats = devfreq->profile->stats;
>> +	parent_stats = parent_devfreq->profile->stats;
>>  	/*
>>  	 * The passive governor have to get the correct frequency from OPP
>>  	 * list of parent device. Because in this case, *freq is temporary
>> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>  	 * Get the OPP table's index of decided freqeuncy by governor
>>  	 * of parent device.
>>  	 */
>> -	for (i = 0; i < parent_devfreq->profile->max_state; i++)
>> -		if (parent_devfreq->profile->freq_table[i] == *freq)
>> +	for (i = 0; i < parent_stats->max_state; i++)
>> +		if (parent_stats->freq_table[i] == *freq)
>>  			break;
>>  
>> -	if (i == parent_devfreq->profile->max_state) {
>> +	if (i == parent_stats->max_state) {
>>  		ret = -EINVAL;
>>  		goto out;
>>  	}
>>  
>>  	/* Get the suitable frequency by using index of parent device. */
>> -	if (i < devfreq->profile->max_state) {
>> -		child_freq = devfreq->profile->freq_table[i];
>> +	if (i < stats->max_state) {
>> +		child_freq = stats->freq_table[i];
>>  	} else {
>> -		count = devfreq->profile->max_state;
>> -		child_freq = devfreq->profile->freq_table[count - 1];
>> +		count = stats->max_state;
>> +		child_freq = stats->freq_table[count - 1];
>>  	}
>>  
>>  	/* Return the suitable frequency for passive device. */
>> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>>  	if (ret < 0)
>>  		goto out;
>>  
>> -	if (devfreq->profile->freq_table
>> +	if (devfreq->profile->stats
>>  		&& (devfreq_update_status(devfreq, freq)))
>>  		dev_err(&devfreq->dev,
>>  			"Couldn't update frequency transition information.\n");
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index 4ceb2a517a9c..8459af1a1583 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>>   */
>>  #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1
>>  
>> +/**
>> + * struct devfreq_stats - Devfreq's transitions stats counters
>> + * @freq_table:		Optional list of frequencies to support statistics
>> + *			and freq_table must be generated in ascending order.
>> + * @max_state:		The size of freq_table.
>> + * @total_trans:	Number of devfreq transitions
>> + * @trans_table:	Statistics of devfreq transitions
>> + * @time_in_state:	Statistics of devfreq states
>> + * @last_time:		The last time stats were updated
>> + * @stats_lock:		Lock protecting trans_table, time_in_state,
>> + *			last_time and total_trans used for statistics
>> + */
>> +struct devfreq_stats {
>> +	unsigned long *freq_table;
>> +	unsigned int max_state;
>> +
>> +	/* information for device frequency transition */
>> +	unsigned int total_trans;
>> +	unsigned int *trans_table;
>> +	u64 *time_in_state;
>> +	unsigned long long last_time;
>> +	spinlock_t stats_lock;
>> +};
>> +
>>  /**
>>   * struct devfreq_dev_profile - Devfreq's user device profile
>>   * @initial_freq:	The operating frequency when devfreq_add_device() is
>> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>>   *			from devfreq_remove_device() call. If the user
>>   *			has registered devfreq->nb at a notifier-head,
>>   *			this is the time to unregister it.
>> - * @freq_table:		Optional list of frequencies to support statistics
>> - *			and freq_table must be generated in ascending order.
>> - * @max_state:		The size of freq_table.
>> - * @total_trans:	Number of devfreq transitions
>> - * @trans_table:	Statistics of devfreq transitions
>> - * @time_in_state:	Statistics of devfreq states
>> - * @last_time:		The last time stats were updated
>> - * @stats_lock:		Lock protecting trans_table, time_in_state,
>> - *			last_time and total_trans used for statistics
>> + * @stats:		Statistics of devfreq states and state transitions
>>   */
>>  struct devfreq_dev_profile {
>>  	unsigned long initial_freq;
>> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>>  	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>>  	void (*exit)(struct device *dev);
>>  
>> -	unsigned long *freq_table;
>> -	unsigned int max_state;
>> -	/* information for device frequency transition */
>> -	unsigned int total_trans;
>> -	unsigned int *trans_table;
>> -	u64 *time_in_state;
>> -	unsigned long long last_time;
>> -	spinlock_t stats_lock;
>> +	struct devfreq_stats *stats;
>>  };
>>  
>>  /**
>>

Chanwoo Choi Nov. 15, 2019, 3:25 a.m. UTC | #3

Hi Bartlomiej,

On 11/15/19 3:01 AM, Bartlomiej Zolnierkiewicz wrote:
> 
> Hi Chanwoo,
> 
> On 11/14/19 2:52 AM, Chanwoo Choi wrote:
>> Hi Kamil,
>>
>> The 'freq_table' and 'max_state' in the devfreq_dev_profile
>> were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
>> device driver was posted to mainline kernel, they used
>> them for a long time. It means that this patch break
>> the compatibility. The ARM Mali drivers are very
>> important devfreq device driver. 
> 
> This argument is not a a technical one and the official upstream
> kernel policy is to not depend on out-of-tree drivers.
> 
> Besides the ARM Mali drivers are full of code like:
> 
> #if LINUX_VERSION_CODE >= KERNEL_VERSION(x, y, z)
> ...
> #else
> ...
> #endif
> 
> so few more instances of similar code won't do any harm.. ;-)
> 
>> [1] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
>> [2] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
>> [3] https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel
> 
> I took a look at ARM Mali drivers source code anyway and I fail to
> see a rationale behind their behavior of doing 'freq_table' and
> 'max_state' initialization in the driver itself (instead of leaving
> it up to the devfreq core code, like all in-kernel drivers are doing
> already).
> 
> Could you please explain rationale behind ARM Mali drivers' special
> needs?
> 
> [ Both ARM Mali and devfreq core code are using generic PM OPP code
>   these days to do 'freq_table' and 'max_state' initialization, the
>   only difference seems to be that ARM Mali creates the frequency
>   table in the descending order (but there also seems to be no real
>   need for it). ]
> 
> Maybe this is an opportunity to simplify also the ARM Mali driver?

OK. I agree to simplify them on this time.
For touching the 'freq_table' and 'max_state', need to fix
the descending order of freq_table. 

The partition_enable_ops() in the drivers/thermal/devfreq_cooling.c 
requires the descending order of freq_table. Have to change it by using
the ascending time or support both ascending and descending order for freq_table.

1. Move freq_table, max_state of devfreq_dev_profile to struct devfreq
2. Edit partition_enable_ops() in the drivers/thermal/devfreq_cooling.c 
   by using ascending order instead of descending order.

> 
>> Also, the devfreq device driver specifies their own
>> information and data into devfreq_dev_profile structure 
>> before registering the devfreq device with devfreq_add_device().
>> This patch breaks the basic usage rule of devfreq_dev_profile structure.
> 
> Well, 'struct devfreq_stats *stats' can be trivially moved out of
> 'struct devfreq_profile' to 'struct devfreq' if you prefer it that
> way..
> 
> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
> 
>> So, I can't agree this patch. Not ack.
>>
>> Regards,
>> Chanwoo Choi
>>
>> On 11/13/19 6:13 PM, Kamil Konieczny wrote:
>>> Count time and transitions between devfreq frequencies in separate struct
>>> for improved code readability and maintenance.
>>>
>>> Signed-off-by: Kamil Konieczny <[e-mail]>
>>> ---
>>>  drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>>>  drivers/devfreq/exynos-bus.c       |   6 +-
>>>  drivers/devfreq/governor_passive.c |  26 +++--
>>>  include/linux/devfreq.h            |  43 ++++----
>>>  4 files changed, 129 insertions(+), 102 deletions(-)
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index d79412b0de59..d85867a91230 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>>   */
>>>  static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>  {
>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>  	int lev;
>>>  
>>> -	for (lev = 0; lev < devfreq->profile->max_state; lev++)
>>> -		if (freq == devfreq->profile->freq_table[lev])
>>> +	for (lev = 0; lev < stats->max_state; lev++)
>>> +		if (freq == stats->freq_table[lev])
>>>  			return lev;
>>>  
>>>  	return -EINVAL;
>>> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>  static int set_freq_table(struct devfreq *devfreq)
>>>  {
>>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>>> +	struct devfreq_stats *stats;
>>>  	struct dev_pm_opp *opp;
>>>  	unsigned long freq;
>>> -	int i, count;
>>> +	int i, count, err = -ENOMEM;
>>>  
>>>  	/* Initialize the freq_table from OPP table */
>>>  	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>>>  	if (count <= 0)
>>>  		return -EINVAL;
>>>  
>>> -	profile->max_state = count;
>>> -	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
>>> -					count,
>>> -					sizeof(*profile->freq_table),
>>> -					GFP_KERNEL);
>>> -	if (!profile->freq_table) {
>>> -		profile->max_state = 0;
>>> +	stats = devm_kzalloc(devfreq->dev.parent,
>>> +			     sizeof(struct devfreq_stats), GFP_KERNEL);
>>> +	if (!stats)
>>>  		return -ENOMEM;
>>> -	}
>>>  
>>> -	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
>>> +	profile->stats = stats;
>>> +	stats->max_state = count;
>>> +	stats->freq_table = devm_kcalloc(devfreq->dev.parent,
>>> +					 count,
>>> +					 sizeof(*stats->freq_table),
>>> +					 GFP_KERNEL);
>>> +	if (!stats->freq_table)
>>> +		goto err_no_mem;
>>> +
>>> +	for (i = 0, freq = 0; i < count; i++, freq++) {
>>>  		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>>>  		if (IS_ERR(opp)) {
>>> -			devm_kfree(devfreq->dev.parent, profile->freq_table);
>>> -			profile->max_state = 0;
>>> -			return PTR_ERR(opp);
>>> +			devm_kfree(devfreq->dev.parent, stats->freq_table);
>>> +			stats->max_state = 0;
>>> +			err = PTR_ERR(opp);
>>> +			goto err_no_mem;
>>>  		}
>>>  		dev_pm_opp_put(opp);
>>> -		profile->freq_table[i] = freq;
>>> +		stats->freq_table[i] = freq;
>>>  	}
>>>  
>>> -	profile->trans_table = devm_kzalloc(devfreq->dev.parent,
>>> -					    array3_size(sizeof(unsigned int),
>>> -							count, count),
>>> -					    GFP_KERNEL);
>>> -	if (!profile->trans_table)
>>> +	stats->trans_table = devm_kzalloc(devfreq->dev.parent,
>>> +					  array3_size(sizeof(unsigned int),
>>> +						      count, count),
>>> +					  GFP_KERNEL);
>>> +	if (!stats->trans_table)
>>>  		goto err_no_mem;
>>>  
>>> -	profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>> -					      sizeof(*profile->time_in_state),
>>> -					      GFP_KERNEL);
>>> -	if (!profile->time_in_state)
>>> +	stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>> +					    sizeof(*stats->time_in_state),
>>> +					    GFP_KERNEL);
>>> +	if (!stats->time_in_state)
>>>  		goto err_no_mem;
>>>  
>>> -	profile->last_time = get_jiffies_64();
>>> -	spin_lock_init(&profile->stats_lock);
>>> +	stats->last_time = get_jiffies_64();
>>> +	spin_lock_init(&stats->stats_lock);
>>>  
>>>  	return 0;
>>>  err_no_mem:
>>> -	profile->max_state = 0;
>>> -	return -ENOMEM;
>>> +	stats->max_state = 0;
>>> +	devm_kfree(devfreq->dev.parent, profile->stats);
>>> +	profile->stats = NULL;
>>> +	return err;
>>>  }
>>>  
>>>  /**
>>> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>>   */
>>>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>  {
>>> -	struct devfreq_dev_profile *profile = devfreq->profile;
>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>  	unsigned long long cur_time;
>>>  	int lev, prev_lev, ret = 0;
>>>  
>>> @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>  
>>>  	/* Immediately exit if previous_freq is not initialized yet. */
>>>  	if (!devfreq->previous_freq) {
>>> -		spin_lock(&profile->stats_lock);
>>> -		profile->last_time = cur_time;
>>> -		spin_unlock(&profile->stats_lock);
>>> +		spin_lock(&stats->stats_lock);
>>> +		stats->last_time = cur_time;
>>> +		spin_unlock(&stats->stats_lock);
>>>  		return 0;
>>>  	}
>>>  
>>>  	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>>>  
>>> -	spin_lock(&profile->stats_lock);
>>> +	spin_lock(&stats->stats_lock);
>>>  	if (prev_lev < 0) {
>>>  		ret = prev_lev;
>>>  		goto out;
>>>  	}
>>>  
>>> -	profile->time_in_state[prev_lev] +=
>>> -			 cur_time - profile->last_time;
>>> +	stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>>>  	lev = devfreq_get_freq_level(devfreq, freq);
>>>  	if (lev < 0) {
>>>  		ret = lev;
>>> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>  	}
>>>  
>>>  	if (lev != prev_lev) {
>>> -		profile->trans_table[(prev_lev *
>>> -				profile->max_state) + lev]++;
>>> -		profile->total_trans++;
>>> +		stats->trans_table[(prev_lev *
>>> +				stats->max_state) + lev]++;
>>> +		stats->total_trans++;
>>>  	}
>>>  
>>>  out:
>>> -	profile->last_time = cur_time;
>>> -	spin_unlock(&profile->stats_lock);
>>> +	stats->last_time = cur_time;
>>> +	spin_unlock(&stats->stats_lock);
>>>  	return ret;
>>>  }
>>>  EXPORT_SYMBOL(devfreq_update_status);
>>> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>>  		queue_delayed_work(devfreq_wq, &devfreq->work,
>>>  			msecs_to_jiffies(profile->polling_ms));
>>>  
>>> -	spin_lock(&profile->stats_lock);
>>> -	profile->last_time = get_jiffies_64();
>>> -	spin_unlock(&profile->stats_lock);
>>> +	spin_lock(&profile->stats->stats_lock);
>>> +	profile->stats->last_time = get_jiffies_64();
>>> +	spin_unlock(&profile->stats->stats_lock);
>>>  	devfreq->stop_polling = false;
>>>  
>>>  	if (profile->get_cur_freq &&
>>> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>>  	devfreq->data = data;
>>>  	devfreq->nb.notifier_call = devfreq_notifier_call;
>>>  
>>> -	if (!profile->max_state && !profile->freq_table) {
>>> +	if (!profile->stats) {
>>>  		mutex_unlock(&devfreq->lock);
>>>  		err = set_freq_table(devfreq);
>>>  		if (err < 0)
>>> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>  			      const char *buf, size_t count)
>>>  {
>>>  	struct devfreq *df = to_devfreq(dev);
>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>  	unsigned long value;
>>>  	int ret;
>>>  
>>> @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>  			goto unlock;
>>>  		}
>>>  	} else {
>>> -		unsigned long *freq_table = df->profile->freq_table;
>>> +		unsigned long *freq_table = stats->freq_table;
>>>  
>>>  		/* Get minimum frequency according to sorting order */
>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>>  			value = freq_table[0];
>>>  		else
>>> -			value = freq_table[df->profile->max_state - 1];
>>> +			value = freq_table[stats->max_state - 1];
>>>  	}
>>>  
>>>  	df->min_freq = value;
>>> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>  			      const char *buf, size_t count)
>>>  {
>>>  	struct devfreq *df = to_devfreq(dev);
>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>  	unsigned long value;
>>>  	int ret;
>>>  
>>> @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>  			goto unlock;
>>>  		}
>>>  	} else {
>>> -		unsigned long *freq_table = df->profile->freq_table;
>>> +		unsigned long *freq_table = stats->freq_table;
>>>  
>>>  		/* Get maximum frequency according to sorting order */
>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>> -			value = freq_table[df->profile->max_state - 1];
>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>> +			value = freq_table[stats->max_state - 1];
>>>  		else
>>>  			value = freq_table[0];
>>>  	}
>>> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>>>  					  char *buf)
>>>  {
>>>  	struct devfreq *df = to_devfreq(d);
>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>  	ssize_t count = 0;
>>>  	int i;
>>>  
>>>  	mutex_lock(&df->lock);
>>>  
>>> -	for (i = 0; i < df->profile->max_state; i++)
>>> +	for (i = 0; i < stats->max_state; i++)
>>>  		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
>>> -				"%lu ", df->profile->freq_table[i]);
>>> +				"%lu ", stats->freq_table[i]);
>>>  
>>>  	mutex_unlock(&df->lock);
>>>  	/* Truncate the trailing space */
>>> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>>  {
>>>  	struct devfreq *devfreq = to_devfreq(dev);
>>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>>> +	struct devfreq_stats *stats = profile->stats;
>>> +	unsigned int max_state = stats->max_state;
>>>  	ssize_t len;
>>>  	int i, j;
>>> -	unsigned int max_state = profile->max_state;
>>>  
>>>  	if (!devfreq->stop_polling &&
>>>  			devfreq_update_status(devfreq, devfreq->previous_freq))
>>> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>>>  	len = sprintf(buf, "     From  :   To\n");
>>>  	len += sprintf(buf + len, "           :");
>>>  
>>> -	spin_lock(&profile->stats_lock);
>>> +	spin_lock(&stats->stats_lock);
>>>  	for (i = 0; i < max_state; i++)
>>>  		len += sprintf(buf + len, "%10lu",
>>> -				profile->freq_table[i]);
>>> +				stats->freq_table[i]);
>>>  
>>>  	len += sprintf(buf + len, "   time(ms)\n");
>>>  
>>>  	for (i = 0; i < max_state; i++) {
>>> -		if (profile->freq_table[i] == devfreq->previous_freq)
>>> +		if (stats->freq_table[i] == devfreq->previous_freq)
>>>  			len += sprintf(buf + len, "*");
>>>  		else
>>>  			len += sprintf(buf + len, " ");
>>>  
>>>  		len += sprintf(buf + len, "%10lu:",
>>> -				profile->freq_table[i]);
>>> +				stats->freq_table[i]);
>>>  		for (j = 0; j < max_state; j++)
>>>  			len += sprintf(buf + len, "%10u",
>>> -				profile->trans_table[(i * max_state) + j]);
>>> +				stats->trans_table[(i * max_state) + j]);
>>>  		len += sprintf(buf + len, "%10llu\n", (u64)
>>> -			jiffies64_to_msecs(profile->time_in_state[i]));
>>> +			jiffies64_to_msecs(stats->time_in_state[i]));
>>>  	}
>>>  
>>>  	len += sprintf(buf + len, "Total transition : %u\n",
>>> -					profile->total_trans);
>>> -	spin_unlock(&profile->stats_lock);
>>> +					stats->total_trans);
>>> +	spin_unlock(&stats->stats_lock);
>>>  	return len;
>>>  }
>>>  static DEVICE_ATTR_RO(trans_stat);
>>>  
>>> -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
>>> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>>>  {
>>> -	unsigned int count = profile->max_state;
>>> -
>>> -	spin_lock(&profile->stats_lock);
>>> -	memset(profile->time_in_state, 0, count * sizeof(u64));
>>> -	memset(profile->trans_table, 0, count * count * sizeof(int));
>>> -	profile->last_time = get_jiffies_64();
>>> -	profile->total_trans = 0;
>>> -	spin_unlock(&profile->stats_lock);
>>> +	unsigned int count = stats->max_state;
>>> +
>>> +	spin_lock(&stats->stats_lock);
>>> +	memset(stats->time_in_state, 0, count * sizeof(u64));
>>> +	memset(stats->trans_table, 0, count * count * sizeof(int));
>>> +	stats->last_time = get_jiffies_64();
>>> +	stats->total_trans = 0;
>>> +	spin_unlock(&stats->stats_lock);
>>>  }
>>>  
>>>  static ssize_t trans_reset_store(struct device *dev,
>>> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>>>  {
>>>  	struct devfreq *devfreq = to_devfreq(dev);
>>>  
>>> -	defvreq_stats_clear_table(devfreq->profile);
>>> +	defvreq_stats_clear_table(devfreq->profile->stats);
>>>  
>>>  	return count;
>>>  }
>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>> index d9f377912c10..b212aae2bb3e 100644
>>> --- a/drivers/devfreq/exynos-bus.c
>>> +++ b/drivers/devfreq/exynos-bus.c
>>> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>  	}
>>>  
>>>  out:
>>> -	max_state = bus->devfreq->profile->max_state;
>>> -	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>>> -	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>>> +	max_state = profile->stats->max_state;
>>> +	min_freq = (profile->stats->freq_table[0] / 1000);
>>> +	max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>>>  	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>>>  			dev_name(dev), min_freq, max_freq);
>>>  
>>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>>> index 58308948b863..b2d87a88335c 100644
>>> --- a/drivers/devfreq/governor_passive.c
>>> +++ b/drivers/devfreq/governor_passive.c
>>> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>  	struct devfreq_passive_data *p_data
>>>  			= (struct devfreq_passive_data *)devfreq->data;
>>>  	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>>> +	struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
>>> +	struct devfreq_stats *stats;
>>>  	unsigned long child_freq = ULONG_MAX;
>>>  	struct dev_pm_opp *opp;
>>>  	int i, count, ret = 0;
>>> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>  	 * device. And then the index is used for getting the suitable
>>>  	 * new frequency for passive devfreq device.
>>>  	 */
>>> -	if (!devfreq->profile || !devfreq->profile->freq_table
>>> -		|| devfreq->profile->max_state <= 0)
>>> +	if (!devfreq->profile || !devfreq->profile->stats ||
>>> +	    devfreq->profile->stats->max_state <= 0 ||
>>> +	    !parent_devfreq->profile ||	!parent_devfreq->profile->stats ||
>>> +	    parent_devfreq->profile->stats->max_state <= 0)
>>>  		return -EINVAL;
>>>  
>>> +	stats = devfreq->profile->stats;
>>> +	parent_stats = parent_devfreq->profile->stats;
>>>  	/*
>>>  	 * The passive governor have to get the correct frequency from OPP
>>>  	 * list of parent device. Because in this case, *freq is temporary
>>> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>  	 * Get the OPP table's index of decided freqeuncy by governor
>>>  	 * of parent device.
>>>  	 */
>>> -	for (i = 0; i < parent_devfreq->profile->max_state; i++)
>>> -		if (parent_devfreq->profile->freq_table[i] == *freq)
>>> +	for (i = 0; i < parent_stats->max_state; i++)
>>> +		if (parent_stats->freq_table[i] == *freq)
>>>  			break;
>>>  
>>> -	if (i == parent_devfreq->profile->max_state) {
>>> +	if (i == parent_stats->max_state) {
>>>  		ret = -EINVAL;
>>>  		goto out;
>>>  	}
>>>  
>>>  	/* Get the suitable frequency by using index of parent device. */
>>> -	if (i < devfreq->profile->max_state) {
>>> -		child_freq = devfreq->profile->freq_table[i];
>>> +	if (i < stats->max_state) {
>>> +		child_freq = stats->freq_table[i];
>>>  	} else {
>>> -		count = devfreq->profile->max_state;
>>> -		child_freq = devfreq->profile->freq_table[count - 1];
>>> +		count = stats->max_state;
>>> +		child_freq = stats->freq_table[count - 1];
>>>  	}
>>>  
>>>  	/* Return the suitable frequency for passive device. */
>>> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>>>  	if (ret < 0)
>>>  		goto out;
>>>  
>>> -	if (devfreq->profile->freq_table
>>> +	if (devfreq->profile->stats
>>>  		&& (devfreq_update_status(devfreq, freq)))
>>>  		dev_err(&devfreq->dev,
>>>  			"Couldn't update frequency transition information.\n");
>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>> index 4ceb2a517a9c..8459af1a1583 100644
>>> --- a/include/linux/devfreq.h
>>> +++ b/include/linux/devfreq.h
>>> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>>>   */
>>>  #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1
>>>  
>>> +/**
>>> + * struct devfreq_stats - Devfreq's transitions stats counters
>>> + * @freq_table:		Optional list of frequencies to support statistics
>>> + *			and freq_table must be generated in ascending order.
>>> + * @max_state:		The size of freq_table.
>>> + * @total_trans:	Number of devfreq transitions
>>> + * @trans_table:	Statistics of devfreq transitions
>>> + * @time_in_state:	Statistics of devfreq states
>>> + * @last_time:		The last time stats were updated
>>> + * @stats_lock:		Lock protecting trans_table, time_in_state,
>>> + *			last_time and total_trans used for statistics
>>> + */
>>> +struct devfreq_stats {
>>> +	unsigned long *freq_table;
>>> +	unsigned int max_state;
>>> +
>>> +	/* information for device frequency transition */
>>> +	unsigned int total_trans;
>>> +	unsigned int *trans_table;
>>> +	u64 *time_in_state;
>>> +	unsigned long long last_time;
>>> +	spinlock_t stats_lock;
>>> +};
>>> +
>>>  /**
>>>   * struct devfreq_dev_profile - Devfreq's user device profile
>>>   * @initial_freq:	The operating frequency when devfreq_add_device() is
>>> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>>>   *			from devfreq_remove_device() call. If the user
>>>   *			has registered devfreq->nb at a notifier-head,
>>>   *			this is the time to unregister it.
>>> - * @freq_table:		Optional list of frequencies to support statistics
>>> - *			and freq_table must be generated in ascending order.
>>> - * @max_state:		The size of freq_table.
>>> - * @total_trans:	Number of devfreq transitions
>>> - * @trans_table:	Statistics of devfreq transitions
>>> - * @time_in_state:	Statistics of devfreq states
>>> - * @last_time:		The last time stats were updated
>>> - * @stats_lock:		Lock protecting trans_table, time_in_state,
>>> - *			last_time and total_trans used for statistics
>>> + * @stats:		Statistics of devfreq states and state transitions
>>>   */
>>>  struct devfreq_dev_profile {
>>>  	unsigned long initial_freq;
>>> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>>>  	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>>>  	void (*exit)(struct device *dev);
>>>  
>>> -	unsigned long *freq_table;
>>> -	unsigned int max_state;
>>> -	/* information for device frequency transition */
>>> -	unsigned int total_trans;
>>> -	unsigned int *trans_table;
>>> -	u64 *time_in_state;
>>> -	unsigned long long last_time;
>>> -	spinlock_t stats_lock;
>>> +	struct devfreq_stats *stats;
>>>  };
>>>  
>>>  /**
>>>
> 
>

Chanwoo Choi Nov. 15, 2019, 6:21 a.m. UTC | #4

Hi Bartlomiej,

On 11/15/19 12:25 PM, Chanwoo Choi wrote:
> Hi Bartlomiej,
> 
> On 11/15/19 3:01 AM, Bartlomiej Zolnierkiewicz wrote:
>>
>> Hi Chanwoo,
>>
>> On 11/14/19 2:52 AM, Chanwoo Choi wrote:
>>> Hi Kamil,
>>>
>>> The 'freq_table' and 'max_state' in the devfreq_dev_profile
>>> were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
>>> device driver was posted to mainline kernel, they used
>>> them for a long time. It means that this patch break
>>> the compatibility. The ARM Mali drivers are very
>>> important devfreq device driver. 
>>
>> This argument is not a a technical one and the official upstream
>> kernel policy is to not depend on out-of-tree drivers.
>>
>> Besides the ARM Mali drivers are full of code like:
>>
>> #if LINUX_VERSION_CODE >= KERNEL_VERSION(x, y, z)
>> ...
>> #else
>> ...
>> #endif
>>
>> so few more instances of similar code won't do any harm.. ;-)
>>
>>> [1] https://protect2.fireeye.com/url?k=909caa5c-cd52abe8-909d2113-000babdfecba-812f16576c3614a3&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
>>> [2] https://protect2.fireeye.com/url?k=33265f96-6ee85e22-3327d4d9-000babdfecba-44c2daec328712e6&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
>>> [3] https://protect2.fireeye.com/url?k=69bdcab0-3473cb04-69bc41ff-000babdfecba-4b576facf85e0208&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel
>>
>> I took a look at ARM Mali drivers source code anyway and I fail to
>> see a rationale behind their behavior of doing 'freq_table' and
>> 'max_state' initialization in the driver itself (instead of leaving
>> it up to the devfreq core code, like all in-kernel drivers are doing
>> already).
>>
>> Could you please explain rationale behind ARM Mali drivers' special
>> needs?
>>
>> [ Both ARM Mali and devfreq core code are using generic PM OPP code
>>   these days to do 'freq_table' and 'max_state' initialization, the
>>   only difference seems to be that ARM Mali creates the frequency
>>   table in the descending order (but there also seems to be no real
>>   need for it). ]
>>
>> Maybe this is an opportunity to simplify also the ARM Mali driver?
> 
> OK. I agree to simplify them on this time.
> For touching the 'freq_table' and 'max_state', need to fix
> the descending order of freq_table. 
> 
> The partition_enable_ops() in the drivers/thermal/devfreq_cooling.c 
> requires the descending order of freq_table. Have to change it by using
> the ascending time or support both ascending and descending order for freq_table.
> 
> 1. Move freq_table, max_state of devfreq_dev_profile to struct devfreq
> 2. Edit partition_enable_ops() in the drivers/thermal/devfreq_cooling.c 
>    by using ascending order instead of descending order.
> 

After changed about 'freq_table' and 'max_state', the build error
will happen on ARM mail driver because the initialization code of
'freq_table' in ARM mali driver, didn't check the kernel version.

The first devfreq patch provided the 'freq_table' as optional variable
in the 'struct devfreq_dev_profile'. Even if ARM mali driver is out of mainline tree, 
this change seems that break the usage rule of 'freq_table' in 'struct devfreq_dev_profile'.

So, if there are no any beneficial reason, I just keep the current status of 'freq_table'
in order to keep the previous usage rule of 'freq_table' in 'struct devfreq_dev_profile'.

Frankly, I'm note sure that it is necessary. I don't want to make
the side-effect without any useful reason.

But,
Separately, have to fix the ordering issue of partition_enable_ops()
in the drivers/thermal/devfreq_cooling.c.

>>
>>> Also, the devfreq device driver specifies their own
>>> information and data into devfreq_dev_profile structure 
>>> before registering the devfreq device with devfreq_add_device().
>>> This patch breaks the basic usage rule of devfreq_dev_profile structure.
>>
>> Well, 'struct devfreq_stats *stats' can be trivially moved out of
>> 'struct devfreq_profile' to 'struct devfreq' if you prefer it that
>> way..
>>
>> Best regards,
>> --
>> Bartlomiej Zolnierkiewicz
>> Samsung R&D Institute Poland
>> Samsung Electronics
>>
>>> So, I can't agree this patch. Not ack.
>>>
>>> Regards,
>>> Chanwoo Choi
>>>
>>> On 11/13/19 6:13 PM, Kamil Konieczny wrote:
>>>> Count time and transitions between devfreq frequencies in separate struct
>>>> for improved code readability and maintenance.
>>>>
>>>> Signed-off-by: Kamil Konieczny <[e-mail]>
>>>> ---
>>>>  drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>>>>  drivers/devfreq/exynos-bus.c       |   6 +-
>>>>  drivers/devfreq/governor_passive.c |  26 +++--
>>>>  include/linux/devfreq.h            |  43 ++++----
>>>>  4 files changed, 129 insertions(+), 102 deletions(-)
>>>>
>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>> index d79412b0de59..d85867a91230 100644
>>>> --- a/drivers/devfreq/devfreq.c
>>>> +++ b/drivers/devfreq/devfreq.c
>>>> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>>>   */
>>>>  static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>  {
>>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>>  	int lev;
>>>>  
>>>> -	for (lev = 0; lev < devfreq->profile->max_state; lev++)
>>>> -		if (freq == devfreq->profile->freq_table[lev])
>>>> +	for (lev = 0; lev < stats->max_state; lev++)
>>>> +		if (freq == stats->freq_table[lev])
>>>>  			return lev;
>>>>  
>>>>  	return -EINVAL;
>>>> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>  static int set_freq_table(struct devfreq *devfreq)
>>>>  {
>>>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>>>> +	struct devfreq_stats *stats;
>>>>  	struct dev_pm_opp *opp;
>>>>  	unsigned long freq;
>>>> -	int i, count;
>>>> +	int i, count, err = -ENOMEM;
>>>>  
>>>>  	/* Initialize the freq_table from OPP table */
>>>>  	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>>>>  	if (count <= 0)
>>>>  		return -EINVAL;
>>>>  
>>>> -	profile->max_state = count;
>>>> -	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>> -					count,
>>>> -					sizeof(*profile->freq_table),
>>>> -					GFP_KERNEL);
>>>> -	if (!profile->freq_table) {
>>>> -		profile->max_state = 0;
>>>> +	stats = devm_kzalloc(devfreq->dev.parent,
>>>> +			     sizeof(struct devfreq_stats), GFP_KERNEL);
>>>> +	if (!stats)
>>>>  		return -ENOMEM;
>>>> -	}
>>>>  
>>>> -	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
>>>> +	profile->stats = stats;
>>>> +	stats->max_state = count;
>>>> +	stats->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>> +					 count,
>>>> +					 sizeof(*stats->freq_table),
>>>> +					 GFP_KERNEL);
>>>> +	if (!stats->freq_table)
>>>> +		goto err_no_mem;
>>>> +
>>>> +	for (i = 0, freq = 0; i < count; i++, freq++) {
>>>>  		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>>>>  		if (IS_ERR(opp)) {
>>>> -			devm_kfree(devfreq->dev.parent, profile->freq_table);
>>>> -			profile->max_state = 0;
>>>> -			return PTR_ERR(opp);
>>>> +			devm_kfree(devfreq->dev.parent, stats->freq_table);
>>>> +			stats->max_state = 0;
>>>> +			err = PTR_ERR(opp);
>>>> +			goto err_no_mem;
>>>>  		}
>>>>  		dev_pm_opp_put(opp);
>>>> -		profile->freq_table[i] = freq;
>>>> +		stats->freq_table[i] = freq;
>>>>  	}
>>>>  
>>>> -	profile->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>> -					    array3_size(sizeof(unsigned int),
>>>> -							count, count),
>>>> -					    GFP_KERNEL);
>>>> -	if (!profile->trans_table)
>>>> +	stats->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>> +					  array3_size(sizeof(unsigned int),
>>>> +						      count, count),
>>>> +					  GFP_KERNEL);
>>>> +	if (!stats->trans_table)
>>>>  		goto err_no_mem;
>>>>  
>>>> -	profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>> -					      sizeof(*profile->time_in_state),
>>>> -					      GFP_KERNEL);
>>>> -	if (!profile->time_in_state)
>>>> +	stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>> +					    sizeof(*stats->time_in_state),
>>>> +					    GFP_KERNEL);
>>>> +	if (!stats->time_in_state)
>>>>  		goto err_no_mem;
>>>>  
>>>> -	profile->last_time = get_jiffies_64();
>>>> -	spin_lock_init(&profile->stats_lock);
>>>> +	stats->last_time = get_jiffies_64();
>>>> +	spin_lock_init(&stats->stats_lock);
>>>>  
>>>>  	return 0;
>>>>  err_no_mem:
>>>> -	profile->max_state = 0;
>>>> -	return -ENOMEM;
>>>> +	stats->max_state = 0;
>>>> +	devm_kfree(devfreq->dev.parent, profile->stats);
>>>> +	profile->stats = NULL;
>>>> +	return err;
>>>>  }
>>>>  
>>>>  /**
>>>> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>>>   */
>>>>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>  {
>>>> -	struct devfreq_dev_profile *profile = devfreq->profile;
>>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>>  	unsigned long long cur_time;
>>>>  	int lev, prev_lev, ret = 0;
>>>>  
>>>> @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>  
>>>>  	/* Immediately exit if previous_freq is not initialized yet. */
>>>>  	if (!devfreq->previous_freq) {
>>>> -		spin_lock(&profile->stats_lock);
>>>> -		profile->last_time = cur_time;
>>>> -		spin_unlock(&profile->stats_lock);
>>>> +		spin_lock(&stats->stats_lock);
>>>> +		stats->last_time = cur_time;
>>>> +		spin_unlock(&stats->stats_lock);
>>>>  		return 0;
>>>>  	}
>>>>  
>>>>  	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>>>>  
>>>> -	spin_lock(&profile->stats_lock);
>>>> +	spin_lock(&stats->stats_lock);
>>>>  	if (prev_lev < 0) {
>>>>  		ret = prev_lev;
>>>>  		goto out;
>>>>  	}
>>>>  
>>>> -	profile->time_in_state[prev_lev] +=
>>>> -			 cur_time - profile->last_time;
>>>> +	stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>>>>  	lev = devfreq_get_freq_level(devfreq, freq);
>>>>  	if (lev < 0) {
>>>>  		ret = lev;
>>>> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>  	}
>>>>  
>>>>  	if (lev != prev_lev) {
>>>> -		profile->trans_table[(prev_lev *
>>>> -				profile->max_state) + lev]++;
>>>> -		profile->total_trans++;
>>>> +		stats->trans_table[(prev_lev *
>>>> +				stats->max_state) + lev]++;
>>>> +		stats->total_trans++;
>>>>  	}
>>>>  
>>>>  out:
>>>> -	profile->last_time = cur_time;
>>>> -	spin_unlock(&profile->stats_lock);
>>>> +	stats->last_time = cur_time;
>>>> +	spin_unlock(&stats->stats_lock);
>>>>  	return ret;
>>>>  }
>>>>  EXPORT_SYMBOL(devfreq_update_status);
>>>> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>>>  		queue_delayed_work(devfreq_wq, &devfreq->work,
>>>>  			msecs_to_jiffies(profile->polling_ms));
>>>>  
>>>> -	spin_lock(&profile->stats_lock);
>>>> -	profile->last_time = get_jiffies_64();
>>>> -	spin_unlock(&profile->stats_lock);
>>>> +	spin_lock(&profile->stats->stats_lock);
>>>> +	profile->stats->last_time = get_jiffies_64();
>>>> +	spin_unlock(&profile->stats->stats_lock);
>>>>  	devfreq->stop_polling = false;
>>>>  
>>>>  	if (profile->get_cur_freq &&
>>>> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>>>  	devfreq->data = data;
>>>>  	devfreq->nb.notifier_call = devfreq_notifier_call;
>>>>  
>>>> -	if (!profile->max_state && !profile->freq_table) {
>>>> +	if (!profile->stats) {
>>>>  		mutex_unlock(&devfreq->lock);
>>>>  		err = set_freq_table(devfreq);
>>>>  		if (err < 0)
>>>> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>  			      const char *buf, size_t count)
>>>>  {
>>>>  	struct devfreq *df = to_devfreq(dev);
>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>  	unsigned long value;
>>>>  	int ret;
>>>>  
>>>> @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>  			goto unlock;
>>>>  		}
>>>>  	} else {
>>>> -		unsigned long *freq_table = df->profile->freq_table;
>>>> +		unsigned long *freq_table = stats->freq_table;
>>>>  
>>>>  		/* Get minimum frequency according to sorting order */
>>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>  			value = freq_table[0];
>>>>  		else
>>>> -			value = freq_table[df->profile->max_state - 1];
>>>> +			value = freq_table[stats->max_state - 1];
>>>>  	}
>>>>  
>>>>  	df->min_freq = value;
>>>> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>  			      const char *buf, size_t count)
>>>>  {
>>>>  	struct devfreq *df = to_devfreq(dev);
>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>  	unsigned long value;
>>>>  	int ret;
>>>>  
>>>> @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>  			goto unlock;
>>>>  		}
>>>>  	} else {
>>>> -		unsigned long *freq_table = df->profile->freq_table;
>>>> +		unsigned long *freq_table = stats->freq_table;
>>>>  
>>>>  		/* Get maximum frequency according to sorting order */
>>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>> -			value = freq_table[df->profile->max_state - 1];
>>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>>> +			value = freq_table[stats->max_state - 1];
>>>>  		else
>>>>  			value = freq_table[0];
>>>>  	}
>>>> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>>>>  					  char *buf)
>>>>  {
>>>>  	struct devfreq *df = to_devfreq(d);
>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>  	ssize_t count = 0;
>>>>  	int i;
>>>>  
>>>>  	mutex_lock(&df->lock);
>>>>  
>>>> -	for (i = 0; i < df->profile->max_state; i++)
>>>> +	for (i = 0; i < stats->max_state; i++)
>>>>  		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
>>>> -				"%lu ", df->profile->freq_table[i]);
>>>> +				"%lu ", stats->freq_table[i]);
>>>>  
>>>>  	mutex_unlock(&df->lock);
>>>>  	/* Truncate the trailing space */
>>>> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>  {
>>>>  	struct devfreq *devfreq = to_devfreq(dev);
>>>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>>>> +	struct devfreq_stats *stats = profile->stats;
>>>> +	unsigned int max_state = stats->max_state;
>>>>  	ssize_t len;
>>>>  	int i, j;
>>>> -	unsigned int max_state = profile->max_state;
>>>>  
>>>>  	if (!devfreq->stop_polling &&
>>>>  			devfreq_update_status(devfreq, devfreq->previous_freq))
>>>> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>  	len = sprintf(buf, "     From  :   To\n");
>>>>  	len += sprintf(buf + len, "           :");
>>>>  
>>>> -	spin_lock(&profile->stats_lock);
>>>> +	spin_lock(&stats->stats_lock);
>>>>  	for (i = 0; i < max_state; i++)
>>>>  		len += sprintf(buf + len, "%10lu",
>>>> -				profile->freq_table[i]);
>>>> +				stats->freq_table[i]);
>>>>  
>>>>  	len += sprintf(buf + len, "   time(ms)\n");
>>>>  
>>>>  	for (i = 0; i < max_state; i++) {
>>>> -		if (profile->freq_table[i] == devfreq->previous_freq)
>>>> +		if (stats->freq_table[i] == devfreq->previous_freq)
>>>>  			len += sprintf(buf + len, "*");
>>>>  		else
>>>>  			len += sprintf(buf + len, " ");
>>>>  
>>>>  		len += sprintf(buf + len, "%10lu:",
>>>> -				profile->freq_table[i]);
>>>> +				stats->freq_table[i]);
>>>>  		for (j = 0; j < max_state; j++)
>>>>  			len += sprintf(buf + len, "%10u",
>>>> -				profile->trans_table[(i * max_state) + j]);
>>>> +				stats->trans_table[(i * max_state) + j]);
>>>>  		len += sprintf(buf + len, "%10llu\n", (u64)
>>>> -			jiffies64_to_msecs(profile->time_in_state[i]));
>>>> +			jiffies64_to_msecs(stats->time_in_state[i]));
>>>>  	}
>>>>  
>>>>  	len += sprintf(buf + len, "Total transition : %u\n",
>>>> -					profile->total_trans);
>>>> -	spin_unlock(&profile->stats_lock);
>>>> +					stats->total_trans);
>>>> +	spin_unlock(&stats->stats_lock);
>>>>  	return len;
>>>>  }
>>>>  static DEVICE_ATTR_RO(trans_stat);
>>>>  
>>>> -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
>>>> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>>>>  {
>>>> -	unsigned int count = profile->max_state;
>>>> -
>>>> -	spin_lock(&profile->stats_lock);
>>>> -	memset(profile->time_in_state, 0, count * sizeof(u64));
>>>> -	memset(profile->trans_table, 0, count * count * sizeof(int));
>>>> -	profile->last_time = get_jiffies_64();
>>>> -	profile->total_trans = 0;
>>>> -	spin_unlock(&profile->stats_lock);
>>>> +	unsigned int count = stats->max_state;
>>>> +
>>>> +	spin_lock(&stats->stats_lock);
>>>> +	memset(stats->time_in_state, 0, count * sizeof(u64));
>>>> +	memset(stats->trans_table, 0, count * count * sizeof(int));
>>>> +	stats->last_time = get_jiffies_64();
>>>> +	stats->total_trans = 0;
>>>> +	spin_unlock(&stats->stats_lock);
>>>>  }
>>>>  
>>>>  static ssize_t trans_reset_store(struct device *dev,
>>>> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>>>>  {
>>>>  	struct devfreq *devfreq = to_devfreq(dev);
>>>>  
>>>> -	defvreq_stats_clear_table(devfreq->profile);
>>>> +	defvreq_stats_clear_table(devfreq->profile->stats);
>>>>  
>>>>  	return count;
>>>>  }
>>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>>> index d9f377912c10..b212aae2bb3e 100644
>>>> --- a/drivers/devfreq/exynos-bus.c
>>>> +++ b/drivers/devfreq/exynos-bus.c
>>>> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>>  	}
>>>>  
>>>>  out:
>>>> -	max_state = bus->devfreq->profile->max_state;
>>>> -	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>>>> -	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>>>> +	max_state = profile->stats->max_state;
>>>> +	min_freq = (profile->stats->freq_table[0] / 1000);
>>>> +	max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>>>>  	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>>>>  			dev_name(dev), min_freq, max_freq);
>>>>  
>>>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>>>> index 58308948b863..b2d87a88335c 100644
>>>> --- a/drivers/devfreq/governor_passive.c
>>>> +++ b/drivers/devfreq/governor_passive.c
>>>> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>  	struct devfreq_passive_data *p_data
>>>>  			= (struct devfreq_passive_data *)devfreq->data;
>>>>  	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>>>> +	struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
>>>> +	struct devfreq_stats *stats;
>>>>  	unsigned long child_freq = ULONG_MAX;
>>>>  	struct dev_pm_opp *opp;
>>>>  	int i, count, ret = 0;
>>>> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>  	 * device. And then the index is used for getting the suitable
>>>>  	 * new frequency for passive devfreq device.
>>>>  	 */
>>>> -	if (!devfreq->profile || !devfreq->profile->freq_table
>>>> -		|| devfreq->profile->max_state <= 0)
>>>> +	if (!devfreq->profile || !devfreq->profile->stats ||
>>>> +	    devfreq->profile->stats->max_state <= 0 ||
>>>> +	    !parent_devfreq->profile ||	!parent_devfreq->profile->stats ||
>>>> +	    parent_devfreq->profile->stats->max_state <= 0)
>>>>  		return -EINVAL;
>>>>  
>>>> +	stats = devfreq->profile->stats;
>>>> +	parent_stats = parent_devfreq->profile->stats;
>>>>  	/*
>>>>  	 * The passive governor have to get the correct frequency from OPP
>>>>  	 * list of parent device. Because in this case, *freq is temporary
>>>> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>  	 * Get the OPP table's index of decided freqeuncy by governor
>>>>  	 * of parent device.
>>>>  	 */
>>>> -	for (i = 0; i < parent_devfreq->profile->max_state; i++)
>>>> -		if (parent_devfreq->profile->freq_table[i] == *freq)
>>>> +	for (i = 0; i < parent_stats->max_state; i++)
>>>> +		if (parent_stats->freq_table[i] == *freq)
>>>>  			break;
>>>>  
>>>> -	if (i == parent_devfreq->profile->max_state) {
>>>> +	if (i == parent_stats->max_state) {
>>>>  		ret = -EINVAL;
>>>>  		goto out;
>>>>  	}
>>>>  
>>>>  	/* Get the suitable frequency by using index of parent device. */
>>>> -	if (i < devfreq->profile->max_state) {
>>>> -		child_freq = devfreq->profile->freq_table[i];
>>>> +	if (i < stats->max_state) {
>>>> +		child_freq = stats->freq_table[i];
>>>>  	} else {
>>>> -		count = devfreq->profile->max_state;
>>>> -		child_freq = devfreq->profile->freq_table[count - 1];
>>>> +		count = stats->max_state;
>>>> +		child_freq = stats->freq_table[count - 1];
>>>>  	}
>>>>  
>>>>  	/* Return the suitable frequency for passive device. */
>>>> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>>>>  	if (ret < 0)
>>>>  		goto out;
>>>>  
>>>> -	if (devfreq->profile->freq_table
>>>> +	if (devfreq->profile->stats
>>>>  		&& (devfreq_update_status(devfreq, freq)))
>>>>  		dev_err(&devfreq->dev,
>>>>  			"Couldn't update frequency transition information.\n");
>>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>>> index 4ceb2a517a9c..8459af1a1583 100644
>>>> --- a/include/linux/devfreq.h
>>>> +++ b/include/linux/devfreq.h
>>>> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>>>>   */
>>>>  #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1
>>>>  
>>>> +/**
>>>> + * struct devfreq_stats - Devfreq's transitions stats counters
>>>> + * @freq_table:		Optional list of frequencies to support statistics
>>>> + *			and freq_table must be generated in ascending order.
>>>> + * @max_state:		The size of freq_table.
>>>> + * @total_trans:	Number of devfreq transitions
>>>> + * @trans_table:	Statistics of devfreq transitions
>>>> + * @time_in_state:	Statistics of devfreq states
>>>> + * @last_time:		The last time stats were updated
>>>> + * @stats_lock:		Lock protecting trans_table, time_in_state,
>>>> + *			last_time and total_trans used for statistics
>>>> + */
>>>> +struct devfreq_stats {
>>>> +	unsigned long *freq_table;
>>>> +	unsigned int max_state;
>>>> +
>>>> +	/* information for device frequency transition */
>>>> +	unsigned int total_trans;
>>>> +	unsigned int *trans_table;
>>>> +	u64 *time_in_state;
>>>> +	unsigned long long last_time;
>>>> +	spinlock_t stats_lock;
>>>> +};
>>>> +
>>>>  /**
>>>>   * struct devfreq_dev_profile - Devfreq's user device profile
>>>>   * @initial_freq:	The operating frequency when devfreq_add_device() is
>>>> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>>>>   *			from devfreq_remove_device() call. If the user
>>>>   *			has registered devfreq->nb at a notifier-head,
>>>>   *			this is the time to unregister it.
>>>> - * @freq_table:		Optional list of frequencies to support statistics
>>>> - *			and freq_table must be generated in ascending order.
>>>> - * @max_state:		The size of freq_table.
>>>> - * @total_trans:	Number of devfreq transitions
>>>> - * @trans_table:	Statistics of devfreq transitions
>>>> - * @time_in_state:	Statistics of devfreq states
>>>> - * @last_time:		The last time stats were updated
>>>> - * @stats_lock:		Lock protecting trans_table, time_in_state,
>>>> - *			last_time and total_trans used for statistics
>>>> + * @stats:		Statistics of devfreq states and state transitions
>>>>   */
>>>>  struct devfreq_dev_profile {
>>>>  	unsigned long initial_freq;
>>>> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>>>>  	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>>>>  	void (*exit)(struct device *dev);
>>>>  
>>>> -	unsigned long *freq_table;
>>>> -	unsigned int max_state;
>>>> -	/* information for device frequency transition */
>>>> -	unsigned int total_trans;
>>>> -	unsigned int *trans_table;
>>>> -	u64 *time_in_state;
>>>> -	unsigned long long last_time;
>>>> -	spinlock_t stats_lock;
>>>> +	struct devfreq_stats *stats;
>>>>  };
>>>>  
>>>>  /**
>>>>
>>
>>
> 
>

Bartlomiej Zolnierkiewicz Nov. 15, 2019, 12:40 p.m. UTC | #5

[ added Zhang, Eduardo, Ørjan and Javi to Cc: ]

On 11/15/19 7:21 AM, Chanwoo Choi wrote:
> Hi Bartlomiej,
> 
> On 11/15/19 12:25 PM, Chanwoo Choi wrote:
>> Hi Bartlomiej,
>>
>> On 11/15/19 3:01 AM, Bartlomiej Zolnierkiewicz wrote:
>>>
>>> Hi Chanwoo,
>>>
>>> On 11/14/19 2:52 AM, Chanwoo Choi wrote:
>>>> Hi Kamil,
>>>>
>>>> The 'freq_table' and 'max_state' in the devfreq_dev_profile
>>>> were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
>>>> device driver was posted to mainline kernel, they used
>>>> them for a long time. It means that this patch break
>>>> the compatibility. The ARM Mali drivers are very
>>>> important devfreq device driver. 
>>>
>>> This argument is not a a technical one and the official upstream
>>> kernel policy is to not depend on out-of-tree drivers.
>>>
>>> Besides the ARM Mali drivers are full of code like:
>>>
>>> #if LINUX_VERSION_CODE >= KERNEL_VERSION(x, y, z)
>>> ...
>>> #else
>>> ...
>>> #endif
>>>
>>> so few more instances of similar code won't do any harm.. ;-)
>>>
>>>> [1] https://protect2.fireeye.com/url?k=909caa5c-cd52abe8-909d2113-000babdfecba-812f16576c3614a3&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
>>>> [2] https://protect2.fireeye.com/url?k=33265f96-6ee85e22-3327d4d9-000babdfecba-44c2daec328712e6&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
>>>> [3] https://protect2.fireeye.com/url?k=69bdcab0-3473cb04-69bc41ff-000babdfecba-4b576facf85e0208&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel
>>>
>>> I took a look at ARM Mali drivers source code anyway and I fail to
>>> see a rationale behind their behavior of doing 'freq_table' and
>>> 'max_state' initialization in the driver itself (instead of leaving
>>> it up to the devfreq core code, like all in-kernel drivers are doing
>>> already).
>>>
>>> Could you please explain rationale behind ARM Mali drivers' special
>>> needs?
>>>
>>> [ Both ARM Mali and devfreq core code are using generic PM OPP code
>>>   these days to do 'freq_table' and 'max_state' initialization, the
>>>   only difference seems to be that ARM Mali creates the frequency
>>>   table in the descending order (but there also seems to be no real
>>>   need for it). ]
>>>
>>> Maybe this is an opportunity to simplify also the ARM Mali driver?
>>
>> OK. I agree to simplify them on this time.
>> For touching the 'freq_table' and 'max_state', need to fix
>> the descending order of freq_table. 
>>
>> The partition_enable_ops() in the drivers/thermal/devfreq_cooling.c 
>> requires the descending order of freq_table. Have to change it by using
>> the ascending time or support both ascending and descending order for freq_table.
>>
>> 1. Move freq_table, max_state of devfreq_dev_profile to struct devfreq
>> 2. Edit partition_enable_ops() in the drivers/thermal/devfreq_cooling.c 
>>    by using ascending order instead of descending order.
>>
> 
> After changed about 'freq_table' and 'max_state', the build error
> will happen on ARM mail driver because the initialization code of
> 'freq_table' in ARM mali driver, didn't check the kernel version.
> 
> The first devfreq patch provided the 'freq_table' as optional variable
> in the 'struct devfreq_dev_profile'. Even if ARM mali driver is out of mainline tree, 
> this change seems that break the usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
> 
> So, if there are no any beneficial reason, I just keep the current status of 'freq_table'
> in order to keep the previous usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
> 
> Frankly, I'm note sure that it is necessary. I don't want to make
> the side-effect without any useful reason.
> 
> But,
> Separately, have to fix the ordering issue of partition_enable_ops()
> in the drivers/thermal/devfreq_cooling.c.

Hmmm.. fixing partition_enable_opps() should be trivial but I wonder
why we are carrying devfreq_cooling.c code in upstream kernel at all?

It has been merged in the following commit:

commit a76caf55e5b356ba20a5a43ac4d9f7a04b20941d
Author: Ørjan Eide <[e-mail]>
Date:   Thu Sep 10 18:09:30 2015 +0100

    thermal: Add devfreq cooling
    
    Add a generic thermal cooling device for devfreq, that is similar to
    cpu_cooling.
    
    The device must use devfreq.  In order to use the power extension of the
    cooling device, it must have registered its OPPs using the OPP library.
    
    Cc: Zhang Rui <[e-mail]>
    Cc: Eduardo Valentin <[e-mail]>
    Signed-off-by: Javi Merino <[e-mail]>
    Signed-off-by: Ørjan Eide <[e-mail]>
    Signed-off-by: Eduardo Valentin <[e-mail]>
...

but 4 years later there is still no single in-kernel user for this code?

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

>>>
>>>> Also, the devfreq device driver specifies their own
>>>> information and data into devfreq_dev_profile structure 
>>>> before registering the devfreq device with devfreq_add_device().
>>>> This patch breaks the basic usage rule of devfreq_dev_profile structure.
>>>
>>> Well, 'struct devfreq_stats *stats' can be trivially moved out of
>>> 'struct devfreq_profile' to 'struct devfreq' if you prefer it that
>>> way..
>>>
>>> Best regards,
>>> --
>>> Bartlomiej Zolnierkiewicz
>>> Samsung R&D Institute Poland
>>> Samsung Electronics
>>>
>>>> So, I can't agree this patch. Not ack.
>>>>
>>>> Regards,
>>>> Chanwoo Choi
>>>>
>>>> On 11/13/19 6:13 PM, Kamil Konieczny wrote:
>>>>> Count time and transitions between devfreq frequencies in separate struct
>>>>> for improved code readability and maintenance.
>>>>>
>>>>> Signed-off-by: Kamil Konieczny <[e-mail]>
>>>>> ---
>>>>>  drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>>>>>  drivers/devfreq/exynos-bus.c       |   6 +-
>>>>>  drivers/devfreq/governor_passive.c |  26 +++--
>>>>>  include/linux/devfreq.h            |  43 ++++----
>>>>>  4 files changed, 129 insertions(+), 102 deletions(-)
>>>>>
>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>>> index d79412b0de59..d85867a91230 100644
>>>>> --- a/drivers/devfreq/devfreq.c
>>>>> +++ b/drivers/devfreq/devfreq.c
>>>>> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>>>>   */
>>>>>  static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>  {
>>>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>  	int lev;
>>>>>  
>>>>> -	for (lev = 0; lev < devfreq->profile->max_state; lev++)
>>>>> -		if (freq == devfreq->profile->freq_table[lev])
>>>>> +	for (lev = 0; lev < stats->max_state; lev++)
>>>>> +		if (freq == stats->freq_table[lev])
>>>>>  			return lev;
>>>>>  
>>>>>  	return -EINVAL;
>>>>> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>  static int set_freq_table(struct devfreq *devfreq)
>>>>>  {
>>>>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>>>>> +	struct devfreq_stats *stats;
>>>>>  	struct dev_pm_opp *opp;
>>>>>  	unsigned long freq;
>>>>> -	int i, count;
>>>>> +	int i, count, err = -ENOMEM;
>>>>>  
>>>>>  	/* Initialize the freq_table from OPP table */
>>>>>  	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>>>>>  	if (count <= 0)
>>>>>  		return -EINVAL;
>>>>>  
>>>>> -	profile->max_state = count;
>>>>> -	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>> -					count,
>>>>> -					sizeof(*profile->freq_table),
>>>>> -					GFP_KERNEL);
>>>>> -	if (!profile->freq_table) {
>>>>> -		profile->max_state = 0;
>>>>> +	stats = devm_kzalloc(devfreq->dev.parent,
>>>>> +			     sizeof(struct devfreq_stats), GFP_KERNEL);
>>>>> +	if (!stats)
>>>>>  		return -ENOMEM;
>>>>> -	}
>>>>>  
>>>>> -	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
>>>>> +	profile->stats = stats;
>>>>> +	stats->max_state = count;
>>>>> +	stats->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>> +					 count,
>>>>> +					 sizeof(*stats->freq_table),
>>>>> +					 GFP_KERNEL);
>>>>> +	if (!stats->freq_table)
>>>>> +		goto err_no_mem;
>>>>> +
>>>>> +	for (i = 0, freq = 0; i < count; i++, freq++) {
>>>>>  		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>>>>>  		if (IS_ERR(opp)) {
>>>>> -			devm_kfree(devfreq->dev.parent, profile->freq_table);
>>>>> -			profile->max_state = 0;
>>>>> -			return PTR_ERR(opp);
>>>>> +			devm_kfree(devfreq->dev.parent, stats->freq_table);
>>>>> +			stats->max_state = 0;
>>>>> +			err = PTR_ERR(opp);
>>>>> +			goto err_no_mem;
>>>>>  		}
>>>>>  		dev_pm_opp_put(opp);
>>>>> -		profile->freq_table[i] = freq;
>>>>> +		stats->freq_table[i] = freq;
>>>>>  	}
>>>>>  
>>>>> -	profile->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>> -					    array3_size(sizeof(unsigned int),
>>>>> -							count, count),
>>>>> -					    GFP_KERNEL);
>>>>> -	if (!profile->trans_table)
>>>>> +	stats->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>> +					  array3_size(sizeof(unsigned int),
>>>>> +						      count, count),
>>>>> +					  GFP_KERNEL);
>>>>> +	if (!stats->trans_table)
>>>>>  		goto err_no_mem;
>>>>>  
>>>>> -	profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>> -					      sizeof(*profile->time_in_state),
>>>>> -					      GFP_KERNEL);
>>>>> -	if (!profile->time_in_state)
>>>>> +	stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>> +					    sizeof(*stats->time_in_state),
>>>>> +					    GFP_KERNEL);
>>>>> +	if (!stats->time_in_state)
>>>>>  		goto err_no_mem;
>>>>>  
>>>>> -	profile->last_time = get_jiffies_64();
>>>>> -	spin_lock_init(&profile->stats_lock);
>>>>> +	stats->last_time = get_jiffies_64();
>>>>> +	spin_lock_init(&stats->stats_lock);
>>>>>  
>>>>>  	return 0;
>>>>>  err_no_mem:
>>>>> -	profile->max_state = 0;
>>>>> -	return -ENOMEM;
>>>>> +	stats->max_state = 0;
>>>>> +	devm_kfree(devfreq->dev.parent, profile->stats);
>>>>> +	profile->stats = NULL;
>>>>> +	return err;
>>>>>  }
>>>>>  
>>>>>  /**
>>>>> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>>>>   */
>>>>>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>  {
>>>>> -	struct devfreq_dev_profile *profile = devfreq->profile;
>>>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>  	unsigned long long cur_time;
>>>>>  	int lev, prev_lev, ret = 0;
>>>>>  
>>>>> @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>  
>>>>>  	/* Immediately exit if previous_freq is not initialized yet. */
>>>>>  	if (!devfreq->previous_freq) {
>>>>> -		spin_lock(&profile->stats_lock);
>>>>> -		profile->last_time = cur_time;
>>>>> -		spin_unlock(&profile->stats_lock);
>>>>> +		spin_lock(&stats->stats_lock);
>>>>> +		stats->last_time = cur_time;
>>>>> +		spin_unlock(&stats->stats_lock);
>>>>>  		return 0;
>>>>>  	}
>>>>>  
>>>>>  	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>>>>>  
>>>>> -	spin_lock(&profile->stats_lock);
>>>>> +	spin_lock(&stats->stats_lock);
>>>>>  	if (prev_lev < 0) {
>>>>>  		ret = prev_lev;
>>>>>  		goto out;
>>>>>  	}
>>>>>  
>>>>> -	profile->time_in_state[prev_lev] +=
>>>>> -			 cur_time - profile->last_time;
>>>>> +	stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>>>>>  	lev = devfreq_get_freq_level(devfreq, freq);
>>>>>  	if (lev < 0) {
>>>>>  		ret = lev;
>>>>> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>  	}
>>>>>  
>>>>>  	if (lev != prev_lev) {
>>>>> -		profile->trans_table[(prev_lev *
>>>>> -				profile->max_state) + lev]++;
>>>>> -		profile->total_trans++;
>>>>> +		stats->trans_table[(prev_lev *
>>>>> +				stats->max_state) + lev]++;
>>>>> +		stats->total_trans++;
>>>>>  	}
>>>>>  
>>>>>  out:
>>>>> -	profile->last_time = cur_time;
>>>>> -	spin_unlock(&profile->stats_lock);
>>>>> +	stats->last_time = cur_time;
>>>>> +	spin_unlock(&stats->stats_lock);
>>>>>  	return ret;
>>>>>  }
>>>>>  EXPORT_SYMBOL(devfreq_update_status);
>>>>> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>>>>  		queue_delayed_work(devfreq_wq, &devfreq->work,
>>>>>  			msecs_to_jiffies(profile->polling_ms));
>>>>>  
>>>>> -	spin_lock(&profile->stats_lock);
>>>>> -	profile->last_time = get_jiffies_64();
>>>>> -	spin_unlock(&profile->stats_lock);
>>>>> +	spin_lock(&profile->stats->stats_lock);
>>>>> +	profile->stats->last_time = get_jiffies_64();
>>>>> +	spin_unlock(&profile->stats->stats_lock);
>>>>>  	devfreq->stop_polling = false;
>>>>>  
>>>>>  	if (profile->get_cur_freq &&
>>>>> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>>>>  	devfreq->data = data;
>>>>>  	devfreq->nb.notifier_call = devfreq_notifier_call;
>>>>>  
>>>>> -	if (!profile->max_state && !profile->freq_table) {
>>>>> +	if (!profile->stats) {
>>>>>  		mutex_unlock(&devfreq->lock);
>>>>>  		err = set_freq_table(devfreq);
>>>>>  		if (err < 0)
>>>>> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>  			      const char *buf, size_t count)
>>>>>  {
>>>>>  	struct devfreq *df = to_devfreq(dev);
>>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>>  	unsigned long value;
>>>>>  	int ret;
>>>>>  
>>>>> @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>  			goto unlock;
>>>>>  		}
>>>>>  	} else {
>>>>> -		unsigned long *freq_table = df->profile->freq_table;
>>>>> +		unsigned long *freq_table = stats->freq_table;
>>>>>  
>>>>>  		/* Get minimum frequency according to sorting order */
>>>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>>  			value = freq_table[0];
>>>>>  		else
>>>>> -			value = freq_table[df->profile->max_state - 1];
>>>>> +			value = freq_table[stats->max_state - 1];
>>>>>  	}
>>>>>  
>>>>>  	df->min_freq = value;
>>>>> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>  			      const char *buf, size_t count)
>>>>>  {
>>>>>  	struct devfreq *df = to_devfreq(dev);
>>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>>  	unsigned long value;
>>>>>  	int ret;
>>>>>  
>>>>> @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>  			goto unlock;
>>>>>  		}
>>>>>  	} else {
>>>>> -		unsigned long *freq_table = df->profile->freq_table;
>>>>> +		unsigned long *freq_table = stats->freq_table;
>>>>>  
>>>>>  		/* Get maximum frequency according to sorting order */
>>>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>> -			value = freq_table[df->profile->max_state - 1];
>>>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>> +			value = freq_table[stats->max_state - 1];
>>>>>  		else
>>>>>  			value = freq_table[0];
>>>>>  	}
>>>>> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>>>>>  					  char *buf)
>>>>>  {
>>>>>  	struct devfreq *df = to_devfreq(d);
>>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>>  	ssize_t count = 0;
>>>>>  	int i;
>>>>>  
>>>>>  	mutex_lock(&df->lock);
>>>>>  
>>>>> -	for (i = 0; i < df->profile->max_state; i++)
>>>>> +	for (i = 0; i < stats->max_state; i++)
>>>>>  		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
>>>>> -				"%lu ", df->profile->freq_table[i]);
>>>>> +				"%lu ", stats->freq_table[i]);
>>>>>  
>>>>>  	mutex_unlock(&df->lock);
>>>>>  	/* Truncate the trailing space */
>>>>> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>  {
>>>>>  	struct devfreq *devfreq = to_devfreq(dev);
>>>>>  	struct devfreq_dev_profile *profile = devfreq->profile;
>>>>> +	struct devfreq_stats *stats = profile->stats;
>>>>> +	unsigned int max_state = stats->max_state;
>>>>>  	ssize_t len;
>>>>>  	int i, j;
>>>>> -	unsigned int max_state = profile->max_state;
>>>>>  
>>>>>  	if (!devfreq->stop_polling &&
>>>>>  			devfreq_update_status(devfreq, devfreq->previous_freq))
>>>>> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>  	len = sprintf(buf, "     From  :   To\n");
>>>>>  	len += sprintf(buf + len, "           :");
>>>>>  
>>>>> -	spin_lock(&profile->stats_lock);
>>>>> +	spin_lock(&stats->stats_lock);
>>>>>  	for (i = 0; i < max_state; i++)
>>>>>  		len += sprintf(buf + len, "%10lu",
>>>>> -				profile->freq_table[i]);
>>>>> +				stats->freq_table[i]);
>>>>>  
>>>>>  	len += sprintf(buf + len, "   time(ms)\n");
>>>>>  
>>>>>  	for (i = 0; i < max_state; i++) {
>>>>> -		if (profile->freq_table[i] == devfreq->previous_freq)
>>>>> +		if (stats->freq_table[i] == devfreq->previous_freq)
>>>>>  			len += sprintf(buf + len, "*");
>>>>>  		else
>>>>>  			len += sprintf(buf + len, " ");
>>>>>  
>>>>>  		len += sprintf(buf + len, "%10lu:",
>>>>> -				profile->freq_table[i]);
>>>>> +				stats->freq_table[i]);
>>>>>  		for (j = 0; j < max_state; j++)
>>>>>  			len += sprintf(buf + len, "%10u",
>>>>> -				profile->trans_table[(i * max_state) + j]);
>>>>> +				stats->trans_table[(i * max_state) + j]);
>>>>>  		len += sprintf(buf + len, "%10llu\n", (u64)
>>>>> -			jiffies64_to_msecs(profile->time_in_state[i]));
>>>>> +			jiffies64_to_msecs(stats->time_in_state[i]));
>>>>>  	}
>>>>>  
>>>>>  	len += sprintf(buf + len, "Total transition : %u\n",
>>>>> -					profile->total_trans);
>>>>> -	spin_unlock(&profile->stats_lock);
>>>>> +					stats->total_trans);
>>>>> +	spin_unlock(&stats->stats_lock);
>>>>>  	return len;
>>>>>  }
>>>>>  static DEVICE_ATTR_RO(trans_stat);
>>>>>  
>>>>> -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
>>>>> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>>>>>  {
>>>>> -	unsigned int count = profile->max_state;
>>>>> -
>>>>> -	spin_lock(&profile->stats_lock);
>>>>> -	memset(profile->time_in_state, 0, count * sizeof(u64));
>>>>> -	memset(profile->trans_table, 0, count * count * sizeof(int));
>>>>> -	profile->last_time = get_jiffies_64();
>>>>> -	profile->total_trans = 0;
>>>>> -	spin_unlock(&profile->stats_lock);
>>>>> +	unsigned int count = stats->max_state;
>>>>> +
>>>>> +	spin_lock(&stats->stats_lock);
>>>>> +	memset(stats->time_in_state, 0, count * sizeof(u64));
>>>>> +	memset(stats->trans_table, 0, count * count * sizeof(int));
>>>>> +	stats->last_time = get_jiffies_64();
>>>>> +	stats->total_trans = 0;
>>>>> +	spin_unlock(&stats->stats_lock);
>>>>>  }
>>>>>  
>>>>>  static ssize_t trans_reset_store(struct device *dev,
>>>>> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>>>>>  {
>>>>>  	struct devfreq *devfreq = to_devfreq(dev);
>>>>>  
>>>>> -	defvreq_stats_clear_table(devfreq->profile);
>>>>> +	defvreq_stats_clear_table(devfreq->profile->stats);
>>>>>  
>>>>>  	return count;
>>>>>  }
>>>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>>>> index d9f377912c10..b212aae2bb3e 100644
>>>>> --- a/drivers/devfreq/exynos-bus.c
>>>>> +++ b/drivers/devfreq/exynos-bus.c
>>>>> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>>>  	}
>>>>>  
>>>>>  out:
>>>>> -	max_state = bus->devfreq->profile->max_state;
>>>>> -	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>>>>> -	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>>>>> +	max_state = profile->stats->max_state;
>>>>> +	min_freq = (profile->stats->freq_table[0] / 1000);
>>>>> +	max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>>>>>  	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>>>>>  			dev_name(dev), min_freq, max_freq);
>>>>>  
>>>>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>>>>> index 58308948b863..b2d87a88335c 100644
>>>>> --- a/drivers/devfreq/governor_passive.c
>>>>> +++ b/drivers/devfreq/governor_passive.c
>>>>> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>  	struct devfreq_passive_data *p_data
>>>>>  			= (struct devfreq_passive_data *)devfreq->data;
>>>>>  	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>>>>> +	struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
>>>>> +	struct devfreq_stats *stats;
>>>>>  	unsigned long child_freq = ULONG_MAX;
>>>>>  	struct dev_pm_opp *opp;
>>>>>  	int i, count, ret = 0;
>>>>> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>  	 * device. And then the index is used for getting the suitable
>>>>>  	 * new frequency for passive devfreq device.
>>>>>  	 */
>>>>> -	if (!devfreq->profile || !devfreq->profile->freq_table
>>>>> -		|| devfreq->profile->max_state <= 0)
>>>>> +	if (!devfreq->profile || !devfreq->profile->stats ||
>>>>> +	    devfreq->profile->stats->max_state <= 0 ||
>>>>> +	    !parent_devfreq->profile ||	!parent_devfreq->profile->stats ||
>>>>> +	    parent_devfreq->profile->stats->max_state <= 0)
>>>>>  		return -EINVAL;
>>>>>  
>>>>> +	stats = devfreq->profile->stats;
>>>>> +	parent_stats = parent_devfreq->profile->stats;
>>>>>  	/*
>>>>>  	 * The passive governor have to get the correct frequency from OPP
>>>>>  	 * list of parent device. Because in this case, *freq is temporary
>>>>> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>  	 * Get the OPP table's index of decided freqeuncy by governor
>>>>>  	 * of parent device.
>>>>>  	 */
>>>>> -	for (i = 0; i < parent_devfreq->profile->max_state; i++)
>>>>> -		if (parent_devfreq->profile->freq_table[i] == *freq)
>>>>> +	for (i = 0; i < parent_stats->max_state; i++)
>>>>> +		if (parent_stats->freq_table[i] == *freq)
>>>>>  			break;
>>>>>  
>>>>> -	if (i == parent_devfreq->profile->max_state) {
>>>>> +	if (i == parent_stats->max_state) {
>>>>>  		ret = -EINVAL;
>>>>>  		goto out;
>>>>>  	}
>>>>>  
>>>>>  	/* Get the suitable frequency by using index of parent device. */
>>>>> -	if (i < devfreq->profile->max_state) {
>>>>> -		child_freq = devfreq->profile->freq_table[i];
>>>>> +	if (i < stats->max_state) {
>>>>> +		child_freq = stats->freq_table[i];
>>>>>  	} else {
>>>>> -		count = devfreq->profile->max_state;
>>>>> -		child_freq = devfreq->profile->freq_table[count - 1];
>>>>> +		count = stats->max_state;
>>>>> +		child_freq = stats->freq_table[count - 1];
>>>>>  	}
>>>>>  
>>>>>  	/* Return the suitable frequency for passive device. */
>>>>> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>>>>>  	if (ret < 0)
>>>>>  		goto out;
>>>>>  
>>>>> -	if (devfreq->profile->freq_table
>>>>> +	if (devfreq->profile->stats
>>>>>  		&& (devfreq_update_status(devfreq, freq)))
>>>>>  		dev_err(&devfreq->dev,
>>>>>  			"Couldn't update frequency transition information.\n");
>>>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>>>> index 4ceb2a517a9c..8459af1a1583 100644
>>>>> --- a/include/linux/devfreq.h
>>>>> +++ b/include/linux/devfreq.h
>>>>> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>>>>>   */
>>>>>  #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1
>>>>>  
>>>>> +/**
>>>>> + * struct devfreq_stats - Devfreq's transitions stats counters
>>>>> + * @freq_table:		Optional list of frequencies to support statistics
>>>>> + *			and freq_table must be generated in ascending order.
>>>>> + * @max_state:		The size of freq_table.
>>>>> + * @total_trans:	Number of devfreq transitions
>>>>> + * @trans_table:	Statistics of devfreq transitions
>>>>> + * @time_in_state:	Statistics of devfreq states
>>>>> + * @last_time:		The last time stats were updated
>>>>> + * @stats_lock:		Lock protecting trans_table, time_in_state,
>>>>> + *			last_time and total_trans used for statistics
>>>>> + */
>>>>> +struct devfreq_stats {
>>>>> +	unsigned long *freq_table;
>>>>> +	unsigned int max_state;
>>>>> +
>>>>> +	/* information for device frequency transition */
>>>>> +	unsigned int total_trans;
>>>>> +	unsigned int *trans_table;
>>>>> +	u64 *time_in_state;
>>>>> +	unsigned long long last_time;
>>>>> +	spinlock_t stats_lock;
>>>>> +};
>>>>> +
>>>>>  /**
>>>>>   * struct devfreq_dev_profile - Devfreq's user device profile
>>>>>   * @initial_freq:	The operating frequency when devfreq_add_device() is
>>>>> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>>>>>   *			from devfreq_remove_device() call. If the user
>>>>>   *			has registered devfreq->nb at a notifier-head,
>>>>>   *			this is the time to unregister it.
>>>>> - * @freq_table:		Optional list of frequencies to support statistics
>>>>> - *			and freq_table must be generated in ascending order.
>>>>> - * @max_state:		The size of freq_table.
>>>>> - * @total_trans:	Number of devfreq transitions
>>>>> - * @trans_table:	Statistics of devfreq transitions
>>>>> - * @time_in_state:	Statistics of devfreq states
>>>>> - * @last_time:		The last time stats were updated
>>>>> - * @stats_lock:		Lock protecting trans_table, time_in_state,
>>>>> - *			last_time and total_trans used for statistics
>>>>> + * @stats:		Statistics of devfreq states and state transitions
>>>>>   */
>>>>>  struct devfreq_dev_profile {
>>>>>  	unsigned long initial_freq;
>>>>> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>>>>>  	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>>>>>  	void (*exit)(struct device *dev);
>>>>>  
>>>>> -	unsigned long *freq_table;
>>>>> -	unsigned int max_state;
>>>>> -	/* information for device frequency transition */
>>>>> -	unsigned int total_trans;
>>>>> -	unsigned int *trans_table;
>>>>> -	u64 *time_in_state;
>>>>> -	unsigned long long last_time;
>>>>> -	spinlock_t stats_lock;
>>>>> +	struct devfreq_stats *stats;
>>>>>  };
>>>>>  
>>>>>  /**
>>>>>

Lukasz Luba Dec. 16, 2019, 1:01 p.m. UTC | #6

Hi Bartek,

[added Dietmar, Robin, Andrzej (for upcoming DRM drm-misc-next)]

On 11/15/19 12:40 PM, Bartlomiej Zolnierkiewicz wrote:
> 
> [ added Zhang, Eduardo, Ørjan and Javi to Cc: ]
> 
> On 11/15/19 7:21 AM, Chanwoo Choi wrote:
>> Hi Bartlomiej,
>>
>> On 11/15/19 12:25 PM, Chanwoo Choi wrote:
>>> Hi Bartlomiej,
>>>
>>> On 11/15/19 3:01 AM, Bartlomiej Zolnierkiewicz wrote:
>>>>
>>>> Hi Chanwoo,
>>>>
>>>> On 11/14/19 2:52 AM, Chanwoo Choi wrote:
>>>>> Hi Kamil,
>>>>>
>>>>> The 'freq_table' and 'max_state' in the devfreq_dev_profile
>>>>> were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
>>>>> device driver was posted to mainline kernel, they used
>>>>> them for a long time. It means that this patch break
>>>>> the compatibility. The ARM Mali drivers are very
>>>>> important devfreq device driver.
>>>>
>>>> This argument is not a a technical one and the official upstream
>>>> kernel policy is to not depend on out-of-tree drivers.
>>>>
>>>> Besides the ARM Mali drivers are full of code like:
>>>>
>>>> #if LINUX_VERSION_CODE >= KERNEL_VERSION(x, y, z)
>>>> ...
>>>> #else
>>>> ...
>>>> #endif
>>>>
>>>> so few more instances of similar code won't do any harm.. ;-)
>>>>
>>>>> [1] https://protect2.fireeye.com/url?k=909caa5c-cd52abe8-909d2113-000babdfecba-812f16576c3614a3&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
>>>>> [2] https://protect2.fireeye.com/url?k=33265f96-6ee85e22-3327d4d9-000babdfecba-44c2daec328712e6&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
>>>>> [3] https://protect2.fireeye.com/url?k=69bdcab0-3473cb04-69bc41ff-000babdfecba-4b576facf85e0208&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel
>>>>
>>>> I took a look at ARM Mali drivers source code anyway and I fail to
>>>> see a rationale behind their behavior of doing 'freq_table' and
>>>> 'max_state' initialization in the driver itself (instead of leaving
>>>> it up to the devfreq core code, like all in-kernel drivers are doing
>>>> already).
>>>>
>>>> Could you please explain rationale behind ARM Mali drivers' special
>>>> needs?
>>>>
>>>> [ Both ARM Mali and devfreq core code are using generic PM OPP code
>>>>    these days to do 'freq_table' and 'max_state' initialization, the
>>>>    only difference seems to be that ARM Mali creates the frequency
>>>>    table in the descending order (but there also seems to be no real
>>>>    need for it). ]
>>>>
>>>> Maybe this is an opportunity to simplify also the ARM Mali driver?
>>>
>>> OK. I agree to simplify them on this time.
>>> For touching the 'freq_table' and 'max_state', need to fix
>>> the descending order of freq_table.
>>>
>>> The partition_enable_ops() in the drivers/thermal/devfreq_cooling.c
>>> requires the descending order of freq_table. Have to change it by using
>>> the ascending time or support both ascending and descending order for freq_table.
>>>
>>> 1. Move freq_table, max_state of devfreq_dev_profile to struct devfreq
>>> 2. Edit partition_enable_ops() in the drivers/thermal/devfreq_cooling.c
>>>     by using ascending order instead of descending order.
>>>
>>
>> After changed about 'freq_table' and 'max_state', the build error
>> will happen on ARM mail driver because the initialization code of
>> 'freq_table' in ARM mali driver, didn't check the kernel version.
>>
>> The first devfreq patch provided the 'freq_table' as optional variable
>> in the 'struct devfreq_dev_profile'. Even if ARM mali driver is out of mainline tree,
>> this change seems that break the usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
>>
>> So, if there are no any beneficial reason, I just keep the current status of 'freq_table'
>> in order to keep the previous usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
>>
>> Frankly, I'm note sure that it is necessary. I don't want to make
>> the side-effect without any useful reason.
>>
>> But,
>> Separately, have to fix the ordering issue of partition_enable_ops()
>> in the drivers/thermal/devfreq_cooling.c.
> 
> Hmmm.. fixing partition_enable_opps() should be trivial but I wonder
> why we are carrying devfreq_cooling.c code in upstream kernel at all?

Well, the devfreq_cooling.c is going to have a client in mainline:
the GPU driver - Panfrost.

It is already in DRM branch 'drm-misc-next':
https://patchwork.freedesktop.org/patch/342848/

Regarding the devfreq_cooling.c code structure.
I am currently working on cleaning up the devfreq cooling code and
adding Energy Model instead for private freq, power tables. It will be
in similar fashion as it is done in cpufreq_cooling. The model will
be also simplified so hopefully more clients would come.
It is under internal review and will be posted shortly.

> 
> It has been merged in the following commit:
> 
> commit a76caf55e5b356ba20a5a43ac4d9f7a04b20941d
> Author: Ørjan Eide <[e-mail]>
> Date:   Thu Sep 10 18:09:30 2015 +0100
> 
>      thermal: Add devfreq cooling
>      
>      Add a generic thermal cooling device for devfreq, that is similar to
>      cpu_cooling.
>      
>      The device must use devfreq.  In order to use the power extension of the
>      cooling device, it must have registered its OPPs using the OPP library.
>      
>      Cc: Zhang Rui <[e-mail]>
>      Cc: Eduardo Valentin <[e-mail]>
>      Signed-off-by: Javi Merino <[e-mail]>
>      Signed-off-by: Ørjan Eide <[e-mail]>
>      Signed-off-by: Eduardo Valentin <[e-mail]>
> ...
> 
> but 4 years later there is still no single in-kernel user for this code?

There will be, via DRM tree.

Regards,
Lukasz

> 
> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
> 
>>>>
>>>>> Also, the devfreq device driver specifies their own
>>>>> information and data into devfreq_dev_profile structure
>>>>> before registering the devfreq device with devfreq_add_device().
>>>>> This patch breaks the basic usage rule of devfreq_dev_profile structure.
>>>>
>>>> Well, 'struct devfreq_stats *stats' can be trivially moved out of
>>>> 'struct devfreq_profile' to 'struct devfreq' if you prefer it that
>>>> way..
>>>>
>>>> Best regards,
>>>> --
>>>> Bartlomiej Zolnierkiewicz
>>>> Samsung R&D Institute Poland
>>>> Samsung Electronics
>>>>
>>>>> So, I can't agree this patch. Not ack.
>>>>>
>>>>> Regards,
>>>>> Chanwoo Choi
>>>>>
>>>>> On 11/13/19 6:13 PM, Kamil Konieczny wrote:
>>>>>> Count time and transitions between devfreq frequencies in separate struct
>>>>>> for improved code readability and maintenance.
>>>>>>
>>>>>> Signed-off-by: Kamil Konieczny <[e-mail]>
>>>>>> ---
>>>>>>   drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>>>>>>   drivers/devfreq/exynos-bus.c       |   6 +-
>>>>>>   drivers/devfreq/governor_passive.c |  26 +++--
>>>>>>   include/linux/devfreq.h            |  43 ++++----
>>>>>>   4 files changed, 129 insertions(+), 102 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>>>> index d79412b0de59..d85867a91230 100644
>>>>>> --- a/drivers/devfreq/devfreq.c
>>>>>> +++ b/drivers/devfreq/devfreq.c
>>>>>> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>>>>>    */
>>>>>>   static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>>   {
>>>>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>>   	int lev;
>>>>>>   
>>>>>> -	for (lev = 0; lev < devfreq->profile->max_state; lev++)
>>>>>> -		if (freq == devfreq->profile->freq_table[lev])
>>>>>> +	for (lev = 0; lev < stats->max_state; lev++)
>>>>>> +		if (freq == stats->freq_table[lev])
>>>>>>   			return lev;
>>>>>>   
>>>>>>   	return -EINVAL;
>>>>>> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>>   static int set_freq_table(struct devfreq *devfreq)
>>>>>>   {
>>>>>>   	struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>> +	struct devfreq_stats *stats;
>>>>>>   	struct dev_pm_opp *opp;
>>>>>>   	unsigned long freq;
>>>>>> -	int i, count;
>>>>>> +	int i, count, err = -ENOMEM;
>>>>>>   
>>>>>>   	/* Initialize the freq_table from OPP table */
>>>>>>   	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>>>>>>   	if (count <= 0)
>>>>>>   		return -EINVAL;
>>>>>>   
>>>>>> -	profile->max_state = count;
>>>>>> -	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>>> -					count,
>>>>>> -					sizeof(*profile->freq_table),
>>>>>> -					GFP_KERNEL);
>>>>>> -	if (!profile->freq_table) {
>>>>>> -		profile->max_state = 0;
>>>>>> +	stats = devm_kzalloc(devfreq->dev.parent,
>>>>>> +			     sizeof(struct devfreq_stats), GFP_KERNEL);
>>>>>> +	if (!stats)
>>>>>>   		return -ENOMEM;
>>>>>> -	}
>>>>>>   
>>>>>> -	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
>>>>>> +	profile->stats = stats;
>>>>>> +	stats->max_state = count;
>>>>>> +	stats->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>>> +					 count,
>>>>>> +					 sizeof(*stats->freq_table),
>>>>>> +					 GFP_KERNEL);
>>>>>> +	if (!stats->freq_table)
>>>>>> +		goto err_no_mem;
>>>>>> +
>>>>>> +	for (i = 0, freq = 0; i < count; i++, freq++) {
>>>>>>   		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>>>>>>   		if (IS_ERR(opp)) {
>>>>>> -			devm_kfree(devfreq->dev.parent, profile->freq_table);
>>>>>> -			profile->max_state = 0;
>>>>>> -			return PTR_ERR(opp);
>>>>>> +			devm_kfree(devfreq->dev.parent, stats->freq_table);
>>>>>> +			stats->max_state = 0;
>>>>>> +			err = PTR_ERR(opp);
>>>>>> +			goto err_no_mem;
>>>>>>   		}
>>>>>>   		dev_pm_opp_put(opp);
>>>>>> -		profile->freq_table[i] = freq;
>>>>>> +		stats->freq_table[i] = freq;
>>>>>>   	}
>>>>>>   
>>>>>> -	profile->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>>> -					    array3_size(sizeof(unsigned int),
>>>>>> -							count, count),
>>>>>> -					    GFP_KERNEL);
>>>>>> -	if (!profile->trans_table)
>>>>>> +	stats->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>>> +					  array3_size(sizeof(unsigned int),
>>>>>> +						      count, count),
>>>>>> +					  GFP_KERNEL);
>>>>>> +	if (!stats->trans_table)
>>>>>>   		goto err_no_mem;
>>>>>>   
>>>>>> -	profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>>> -					      sizeof(*profile->time_in_state),
>>>>>> -					      GFP_KERNEL);
>>>>>> -	if (!profile->time_in_state)
>>>>>> +	stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>>> +					    sizeof(*stats->time_in_state),
>>>>>> +					    GFP_KERNEL);
>>>>>> +	if (!stats->time_in_state)
>>>>>>   		goto err_no_mem;
>>>>>>   
>>>>>> -	profile->last_time = get_jiffies_64();
>>>>>> -	spin_lock_init(&profile->stats_lock);
>>>>>> +	stats->last_time = get_jiffies_64();
>>>>>> +	spin_lock_init(&stats->stats_lock);
>>>>>>   
>>>>>>   	return 0;
>>>>>>   err_no_mem:
>>>>>> -	profile->max_state = 0;
>>>>>> -	return -ENOMEM;
>>>>>> +	stats->max_state = 0;
>>>>>> +	devm_kfree(devfreq->dev.parent, profile->stats);
>>>>>> +	profile->stats = NULL;
>>>>>> +	return err;
>>>>>>   }
>>>>>>   
>>>>>>   /**
>>>>>> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>>>>>    */
>>>>>>   int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>   {
>>>>>> -	struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>> +	struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>>   	unsigned long long cur_time;
>>>>>>   	int lev, prev_lev, ret = 0;
>>>>>>   
>>>>>> @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>   
>>>>>>   	/* Immediately exit if previous_freq is not initialized yet. */
>>>>>>   	if (!devfreq->previous_freq) {
>>>>>> -		spin_lock(&profile->stats_lock);
>>>>>> -		profile->last_time = cur_time;
>>>>>> -		spin_unlock(&profile->stats_lock);
>>>>>> +		spin_lock(&stats->stats_lock);
>>>>>> +		stats->last_time = cur_time;
>>>>>> +		spin_unlock(&stats->stats_lock);
>>>>>>   		return 0;
>>>>>>   	}
>>>>>>   
>>>>>>   	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>>>>>>   
>>>>>> -	spin_lock(&profile->stats_lock);
>>>>>> +	spin_lock(&stats->stats_lock);
>>>>>>   	if (prev_lev < 0) {
>>>>>>   		ret = prev_lev;
>>>>>>   		goto out;
>>>>>>   	}
>>>>>>   
>>>>>> -	profile->time_in_state[prev_lev] +=
>>>>>> -			 cur_time - profile->last_time;
>>>>>> +	stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>>>>>>   	lev = devfreq_get_freq_level(devfreq, freq);
>>>>>>   	if (lev < 0) {
>>>>>>   		ret = lev;
>>>>>> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>   	}
>>>>>>   
>>>>>>   	if (lev != prev_lev) {
>>>>>> -		profile->trans_table[(prev_lev *
>>>>>> -				profile->max_state) + lev]++;
>>>>>> -		profile->total_trans++;
>>>>>> +		stats->trans_table[(prev_lev *
>>>>>> +				stats->max_state) + lev]++;
>>>>>> +		stats->total_trans++;
>>>>>>   	}
>>>>>>   
>>>>>>   out:
>>>>>> -	profile->last_time = cur_time;
>>>>>> -	spin_unlock(&profile->stats_lock);
>>>>>> +	stats->last_time = cur_time;
>>>>>> +	spin_unlock(&stats->stats_lock);
>>>>>>   	return ret;
>>>>>>   }
>>>>>>   EXPORT_SYMBOL(devfreq_update_status);
>>>>>> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>>>>>   		queue_delayed_work(devfreq_wq, &devfreq->work,
>>>>>>   			msecs_to_jiffies(profile->polling_ms));
>>>>>>   
>>>>>> -	spin_lock(&profile->stats_lock);
>>>>>> -	profile->last_time = get_jiffies_64();
>>>>>> -	spin_unlock(&profile->stats_lock);
>>>>>> +	spin_lock(&profile->stats->stats_lock);
>>>>>> +	profile->stats->last_time = get_jiffies_64();
>>>>>> +	spin_unlock(&profile->stats->stats_lock);
>>>>>>   	devfreq->stop_polling = false;
>>>>>>   
>>>>>>   	if (profile->get_cur_freq &&
>>>>>> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>>>>>   	devfreq->data = data;
>>>>>>   	devfreq->nb.notifier_call = devfreq_notifier_call;
>>>>>>   
>>>>>> -	if (!profile->max_state && !profile->freq_table) {
>>>>>> +	if (!profile->stats) {
>>>>>>   		mutex_unlock(&devfreq->lock);
>>>>>>   		err = set_freq_table(devfreq);
>>>>>>   		if (err < 0)
>>>>>> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>   			      const char *buf, size_t count)
>>>>>>   {
>>>>>>   	struct devfreq *df = to_devfreq(dev);
>>>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>>>   	unsigned long value;
>>>>>>   	int ret;
>>>>>>   
>>>>>> @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>   			goto unlock;
>>>>>>   		}
>>>>>>   	} else {
>>>>>> -		unsigned long *freq_table = df->profile->freq_table;
>>>>>> +		unsigned long *freq_table = stats->freq_table;
>>>>>>   
>>>>>>   		/* Get minimum frequency according to sorting order */
>>>>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>>>   			value = freq_table[0];
>>>>>>   		else
>>>>>> -			value = freq_table[df->profile->max_state - 1];
>>>>>> +			value = freq_table[stats->max_state - 1];
>>>>>>   	}
>>>>>>   
>>>>>>   	df->min_freq = value;
>>>>>> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>   			      const char *buf, size_t count)
>>>>>>   {
>>>>>>   	struct devfreq *df = to_devfreq(dev);
>>>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>>>   	unsigned long value;
>>>>>>   	int ret;
>>>>>>   
>>>>>> @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>   			goto unlock;
>>>>>>   		}
>>>>>>   	} else {
>>>>>> -		unsigned long *freq_table = df->profile->freq_table;
>>>>>> +		unsigned long *freq_table = stats->freq_table;
>>>>>>   
>>>>>>   		/* Get maximum frequency according to sorting order */
>>>>>> -		if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>>> -			value = freq_table[df->profile->max_state - 1];
>>>>>> +		if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>>> +			value = freq_table[stats->max_state - 1];
>>>>>>   		else
>>>>>>   			value = freq_table[0];
>>>>>>   	}
>>>>>> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>>>>>>   					  char *buf)
>>>>>>   {
>>>>>>   	struct devfreq *df = to_devfreq(d);
>>>>>> +	struct devfreq_stats *stats = df->profile->stats;
>>>>>>   	ssize_t count = 0;
>>>>>>   	int i;
>>>>>>   
>>>>>>   	mutex_lock(&df->lock);
>>>>>>   
>>>>>> -	for (i = 0; i < df->profile->max_state; i++)
>>>>>> +	for (i = 0; i < stats->max_state; i++)
>>>>>>   		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
>>>>>> -				"%lu ", df->profile->freq_table[i]);
>>>>>> +				"%lu ", stats->freq_table[i]);
>>>>>>   
>>>>>>   	mutex_unlock(&df->lock);
>>>>>>   	/* Truncate the trailing space */
>>>>>> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>>   {
>>>>>>   	struct devfreq *devfreq = to_devfreq(dev);
>>>>>>   	struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>> +	struct devfreq_stats *stats = profile->stats;
>>>>>> +	unsigned int max_state = stats->max_state;
>>>>>>   	ssize_t len;
>>>>>>   	int i, j;
>>>>>> -	unsigned int max_state = profile->max_state;
>>>>>>   
>>>>>>   	if (!devfreq->stop_polling &&
>>>>>>   			devfreq_update_status(devfreq, devfreq->previous_freq))
>>>>>> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>>   	len = sprintf(buf, "     From  :   To\n");
>>>>>>   	len += sprintf(buf + len, "           :");
>>>>>>   
>>>>>> -	spin_lock(&profile->stats_lock);
>>>>>> +	spin_lock(&stats->stats_lock);
>>>>>>   	for (i = 0; i < max_state; i++)
>>>>>>   		len += sprintf(buf + len, "%10lu",
>>>>>> -				profile->freq_table[i]);
>>>>>> +				stats->freq_table[i]);
>>>>>>   
>>>>>>   	len += sprintf(buf + len, "   time(ms)\n");
>>>>>>   
>>>>>>   	for (i = 0; i < max_state; i++) {
>>>>>> -		if (profile->freq_table[i] == devfreq->previous_freq)
>>>>>> +		if (stats->freq_table[i] == devfreq->previous_freq)
>>>>>>   			len += sprintf(buf + len, "*");
>>>>>>   		else
>>>>>>   			len += sprintf(buf + len, " ");
>>>>>>   
>>>>>>   		len += sprintf(buf + len, "%10lu:",
>>>>>> -				profile->freq_table[i]);
>>>>>> +				stats->freq_table[i]);
>>>>>>   		for (j = 0; j < max_state; j++)
>>>>>>   			len += sprintf(buf + len, "%10u",
>>>>>> -				profile->trans_table[(i * max_state) + j]);
>>>>>> +				stats->trans_table[(i * max_state) + j]);
>>>>>>   		len += sprintf(buf + len, "%10llu\n", (u64)
>>>>>> -			jiffies64_to_msecs(profile->time_in_state[i]));
>>>>>> +			jiffies64_to_msecs(stats->time_in_state[i]));
>>>>>>   	}
>>>>>>   
>>>>>>   	len += sprintf(buf + len, "Total transition : %u\n",
>>>>>> -					profile->total_trans);
>>>>>> -	spin_unlock(&profile->stats_lock);
>>>>>> +					stats->total_trans);
>>>>>> +	spin_unlock(&stats->stats_lock);
>>>>>>   	return len;
>>>>>>   }
>>>>>>   static DEVICE_ATTR_RO(trans_stat);
>>>>>>   
>>>>>> -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
>>>>>> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>>>>>>   {
>>>>>> -	unsigned int count = profile->max_state;
>>>>>> -
>>>>>> -	spin_lock(&profile->stats_lock);
>>>>>> -	memset(profile->time_in_state, 0, count * sizeof(u64));
>>>>>> -	memset(profile->trans_table, 0, count * count * sizeof(int));
>>>>>> -	profile->last_time = get_jiffies_64();
>>>>>> -	profile->total_trans = 0;
>>>>>> -	spin_unlock(&profile->stats_lock);
>>>>>> +	unsigned int count = stats->max_state;
>>>>>> +
>>>>>> +	spin_lock(&stats->stats_lock);
>>>>>> +	memset(stats->time_in_state, 0, count * sizeof(u64));
>>>>>> +	memset(stats->trans_table, 0, count * count * sizeof(int));
>>>>>> +	stats->last_time = get_jiffies_64();
>>>>>> +	stats->total_trans = 0;
>>>>>> +	spin_unlock(&stats->stats_lock);
>>>>>>   }
>>>>>>   
>>>>>>   static ssize_t trans_reset_store(struct device *dev,
>>>>>> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>>>>>>   {
>>>>>>   	struct devfreq *devfreq = to_devfreq(dev);
>>>>>>   
>>>>>> -	defvreq_stats_clear_table(devfreq->profile);
>>>>>> +	defvreq_stats_clear_table(devfreq->profile->stats);
>>>>>>   
>>>>>>   	return count;
>>>>>>   }
>>>>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>>>>> index d9f377912c10..b212aae2bb3e 100644
>>>>>> --- a/drivers/devfreq/exynos-bus.c
>>>>>> +++ b/drivers/devfreq/exynos-bus.c
>>>>>> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>>>>   	}
>>>>>>   
>>>>>>   out:
>>>>>> -	max_state = bus->devfreq->profile->max_state;
>>>>>> -	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>>>>>> -	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>>>>>> +	max_state = profile->stats->max_state;
>>>>>> +	min_freq = (profile->stats->freq_table[0] / 1000);
>>>>>> +	max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>>>>>>   	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>>>>>>   			dev_name(dev), min_freq, max_freq);
>>>>>>   
>>>>>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>>>>>> index 58308948b863..b2d87a88335c 100644
>>>>>> --- a/drivers/devfreq/governor_passive.c
>>>>>> +++ b/drivers/devfreq/governor_passive.c
>>>>>> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>   	struct devfreq_passive_data *p_data
>>>>>>   			= (struct devfreq_passive_data *)devfreq->data;
>>>>>>   	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>>>>>> +	struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
>>>>>> +	struct devfreq_stats *stats;
>>>>>>   	unsigned long child_freq = ULONG_MAX;
>>>>>>   	struct dev_pm_opp *opp;
>>>>>>   	int i, count, ret = 0;
>>>>>> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>   	 * device. And then the index is used for getting the suitable
>>>>>>   	 * new frequency for passive devfreq device.
>>>>>>   	 */
>>>>>> -	if (!devfreq->profile || !devfreq->profile->freq_table
>>>>>> -		|| devfreq->profile->max_state <= 0)
>>>>>> +	if (!devfreq->profile || !devfreq->profile->stats ||
>>>>>> +	    devfreq->profile->stats->max_state <= 0 ||
>>>>>> +	    !parent_devfreq->profile ||	!parent_devfreq->profile->stats ||
>>>>>> +	    parent_devfreq->profile->stats->max_state <= 0)
>>>>>>   		return -EINVAL;
>>>>>>   
>>>>>> +	stats = devfreq->profile->stats;
>>>>>> +	parent_stats = parent_devfreq->profile->stats;
>>>>>>   	/*
>>>>>>   	 * The passive governor have to get the correct frequency from OPP
>>>>>>   	 * list of parent device. Because in this case, *freq is temporary
>>>>>> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>   	 * Get the OPP table's index of decided freqeuncy by governor
>>>>>>   	 * of parent device.
>>>>>>   	 */
>>>>>> -	for (i = 0; i < parent_devfreq->profile->max_state; i++)
>>>>>> -		if (parent_devfreq->profile->freq_table[i] == *freq)
>>>>>> +	for (i = 0; i < parent_stats->max_state; i++)
>>>>>> +		if (parent_stats->freq_table[i] == *freq)
>>>>>>   			break;
>>>>>>   
>>>>>> -	if (i == parent_devfreq->profile->max_state) {
>>>>>> +	if (i == parent_stats->max_state) {
>>>>>>   		ret = -EINVAL;
>>>>>>   		goto out;
>>>>>>   	}
>>>>>>   
>>>>>>   	/* Get the suitable frequency by using index of parent device. */
>>>>>> -	if (i < devfreq->profile->max_state) {
>>>>>> -		child_freq = devfreq->profile->freq_table[i];
>>>>>> +	if (i < stats->max_state) {
>>>>>> +		child_freq = stats->freq_table[i];
>>>>>>   	} else {
>>>>>> -		count = devfreq->profile->max_state;
>>>>>> -		child_freq = devfreq->profile->freq_table[count - 1];
>>>>>> +		count = stats->max_state;
>>>>>> +		child_freq = stats->freq_table[count - 1];
>>>>>>   	}
>>>>>>   
>>>>>>   	/* Return the suitable frequency for passive device. */
>>>>>> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>>>>>>   	if (ret < 0)
>>>>>>   		goto out;
>>>>>>   
>>>>>> -	if (devfreq->profile->freq_table
>>>>>> +	if (devfreq->profile->stats
>>>>>>   		&& (devfreq_update_status(devfreq, freq)))
>>>>>>   		dev_err(&devfreq->dev,
>>>>>>   			"Couldn't update frequency transition information.\n");
>>>>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>>>>> index 4ceb2a517a9c..8459af1a1583 100644
>>>>>> --- a/include/linux/devfreq.h
>>>>>> +++ b/include/linux/devfreq.h
>>>>>> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>>>>>>    */
>>>>>>   #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1
>>>>>>   
>>>>>> +/**
>>>>>> + * struct devfreq_stats - Devfreq's transitions stats counters
>>>>>> + * @freq_table:		Optional list of frequencies to support statistics
>>>>>> + *			and freq_table must be generated in ascending order.
>>>>>> + * @max_state:		The size of freq_table.
>>>>>> + * @total_trans:	Number of devfreq transitions
>>>>>> + * @trans_table:	Statistics of devfreq transitions
>>>>>> + * @time_in_state:	Statistics of devfreq states
>>>>>> + * @last_time:		The last time stats were updated
>>>>>> + * @stats_lock:		Lock protecting trans_table, time_in_state,
>>>>>> + *			last_time and total_trans used for statistics
>>>>>> + */
>>>>>> +struct devfreq_stats {
>>>>>> +	unsigned long *freq_table;
>>>>>> +	unsigned int max_state;
>>>>>> +
>>>>>> +	/* information for device frequency transition */
>>>>>> +	unsigned int total_trans;
>>>>>> +	unsigned int *trans_table;
>>>>>> +	u64 *time_in_state;
>>>>>> +	unsigned long long last_time;
>>>>>> +	spinlock_t stats_lock;
>>>>>> +};
>>>>>> +
>>>>>>   /**
>>>>>>    * struct devfreq_dev_profile - Devfreq's user device profile
>>>>>>    * @initial_freq:	The operating frequency when devfreq_add_device() is
>>>>>> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>>>>>>    *			from devfreq_remove_device() call. If the user
>>>>>>    *			has registered devfreq->nb at a notifier-head,
>>>>>>    *			this is the time to unregister it.
>>>>>> - * @freq_table:		Optional list of frequencies to support statistics
>>>>>> - *			and freq_table must be generated in ascending order.
>>>>>> - * @max_state:		The size of freq_table.
>>>>>> - * @total_trans:	Number of devfreq transitions
>>>>>> - * @trans_table:	Statistics of devfreq transitions
>>>>>> - * @time_in_state:	Statistics of devfreq states
>>>>>> - * @last_time:		The last time stats were updated
>>>>>> - * @stats_lock:		Lock protecting trans_table, time_in_state,
>>>>>> - *			last_time and total_trans used for statistics
>>>>>> + * @stats:		Statistics of devfreq states and state transitions
>>>>>>    */
>>>>>>   struct devfreq_dev_profile {
>>>>>>   	unsigned long initial_freq;
>>>>>> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>>>>>>   	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>>>>>>   	void (*exit)(struct device *dev);
>>>>>>   
>>>>>> -	unsigned long *freq_table;
>>>>>> -	unsigned int max_state;
>>>>>> -	/* information for device frequency transition */
>>>>>> -	unsigned int total_trans;
>>>>>> -	unsigned int *trans_table;
>>>>>> -	u64 *time_in_state;
>>>>>> -	unsigned long long last_time;
>>>>>> -	spinlock_t stats_lock;
>>>>>> +	struct devfreq_stats *stats;
>>>>>>   };
>>>>>>   
>>>>>>   /**
>>>>>>
> 
> _______________________________________________
> linux-arm-kernel mailing list
> [e-mail]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

Chanwoo Choi Dec. 17, 2019, 12:07 a.m. UTC | #7

Hi Lukaz,

On 12/16/19 10:01 PM, Lukasz Luba wrote:
> Hi Bartek,
> 
> [added Dietmar, Robin, Andrzej (for upcoming DRM drm-misc-next)]
> 
> On 11/15/19 12:40 PM, Bartlomiej Zolnierkiewicz wrote:
>>
>> [ added Zhang, Eduardo, Ørjan and Javi to Cc: ]
>>
>> On 11/15/19 7:21 AM, Chanwoo Choi wrote:
>>> Hi Bartlomiej,
>>>
>>> On 11/15/19 12:25 PM, Chanwoo Choi wrote:
>>>> Hi Bartlomiej,
>>>>
>>>> On 11/15/19 3:01 AM, Bartlomiej Zolnierkiewicz wrote:
>>>>>
>>>>> Hi Chanwoo,
>>>>>
>>>>> On 11/14/19 2:52 AM, Chanwoo Choi wrote:
>>>>>> Hi Kamil,
>>>>>>
>>>>>> The 'freq_table' and 'max_state' in the devfreq_dev_profile
>>>>>> were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
>>>>>> device driver was posted to mainline kernel, they used
>>>>>> them for a long time. It means that this patch break
>>>>>> the compatibility. The ARM Mali drivers are very
>>>>>> important devfreq device driver.
>>>>>
>>>>> This argument is not a a technical one and the official upstream
>>>>> kernel policy is to not depend on out-of-tree drivers.
>>>>>
>>>>> Besides the ARM Mali drivers are full of code like:
>>>>>
>>>>> #if LINUX_VERSION_CODE >= KERNEL_VERSION(x, y, z)
>>>>> ...
>>>>> #else
>>>>> ...
>>>>> #endif
>>>>>
>>>>> so few more instances of similar code won't do any harm.. ;-)
>>>>>
>>>>>> [1] https://protect2.fireeye.com/url?k=909caa5c-cd52abe8-909d2113-000babdfecba-812f16576c3614a3&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
>>>>>> [2] https://protect2.fireeye.com/url?k=33265f96-6ee85e22-3327d4d9-000babdfecba-44c2daec328712e6&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
>>>>>> [3] https://protect2.fireeye.com/url?k=69bdcab0-3473cb04-69bc41ff-000babdfecba-4b576facf85e0208&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel
>>>>>
>>>>> I took a look at ARM Mali drivers source code anyway and I fail to
>>>>> see a rationale behind their behavior of doing 'freq_table' and
>>>>> 'max_state' initialization in the driver itself (instead of leaving
>>>>> it up to the devfreq core code, like all in-kernel drivers are doing
>>>>> already).
>>>>>
>>>>> Could you please explain rationale behind ARM Mali drivers' special
>>>>> needs?
>>>>>
>>>>> [ Both ARM Mali and devfreq core code are using generic PM OPP code
>>>>>    these days to do 'freq_table' and 'max_state' initialization, the
>>>>>    only difference seems to be that ARM Mali creates the frequency
>>>>>    table in the descending order (but there also seems to be no real
>>>>>    need for it). ]
>>>>>
>>>>> Maybe this is an opportunity to simplify also the ARM Mali driver?
>>>>
>>>> OK. I agree to simplify them on this time.
>>>> For touching the 'freq_table' and 'max_state', need to fix
>>>> the descending order of freq_table.
>>>>
>>>> The partition_enable_ops() in the drivers/thermal/devfreq_cooling.c
>>>> requires the descending order of freq_table. Have to change it by using
>>>> the ascending time or support both ascending and descending order for freq_table.
>>>>
>>>> 1. Move freq_table, max_state of devfreq_dev_profile to struct devfreq
>>>> 2. Edit partition_enable_ops() in the drivers/thermal/devfreq_cooling.c
>>>>     by using ascending order instead of descending order.
>>>>
>>>
>>> After changed about 'freq_table' and 'max_state', the build error
>>> will happen on ARM mail driver because the initialization code of
>>> 'freq_table' in ARM mali driver, didn't check the kernel version.
>>>
>>> The first devfreq patch provided the 'freq_table' as optional variable
>>> in the 'struct devfreq_dev_profile'. Even if ARM mali driver is out of mainline tree,
>>> this change seems that break the usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
>>>
>>> So, if there are no any beneficial reason, I just keep the current status of 'freq_table'
>>> in order to keep the previous usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
>>>
>>> Frankly, I'm note sure that it is necessary. I don't want to make
>>> the side-effect without any useful reason.
>>>
>>> But,
>>> Separately, have to fix the ordering issue of partition_enable_ops()
>>> in the drivers/thermal/devfreq_cooling.c.
>>
>> Hmmm.. fixing partition_enable_opps() should be trivial but I wonder
>> why we are carrying devfreq_cooling.c code in upstream kernel at all?
> 
> Well, the devfreq_cooling.c is going to have a client in mainline:
> the GPU driver - Panfrost.
> 
> It is already in DRM branch 'drm-misc-next':
> https://protect2.fireeye.com/url?k=75a0e087-283b1ce4-75a16bc8-0cc47a31cdbc-4953aa9e0574f6dc&u=https://patchwork.freedesktop.org/patch/342848/
> 
> Regarding the devfreq_cooling.c code structure.
> I am currently working on cleaning up the devfreq cooling code and
> adding Energy Model instead for private freq, power tables. It will be
> in similar fashion as it is done in cpufreq_cooling. The model will
> be also simplified so hopefully more clients would come.
> It is under internal review and will be posted shortly.

Good news about Energy Model. When you send the patch related to Energy model,
please add me to Cc list.

> 
>>
>> It has been merged in the following commit:
>>
>> commit a76caf55e5b356ba20a5a43ac4d9f7a04b20941d
>> Author: Ørjan Eide <[e-mail]>
>> Date:   Thu Sep 10 18:09:30 2015 +0100
>>
>>      thermal: Add devfreq cooling
>>           Add a generic thermal cooling device for devfreq, that is similar to
>>      cpu_cooling.
>>           The device must use devfreq.  In order to use the power extension of the
>>      cooling device, it must have registered its OPPs using the OPP library.
>>           Cc: Zhang Rui <[e-mail]>
>>      Cc: Eduardo Valentin <[e-mail]>
>>      Signed-off-by: Javi Merino <[e-mail]>
>>      Signed-off-by: Ørjan Eide <[e-mail]>
>>      Signed-off-by: Eduardo Valentin <[e-mail]>
>> ...
>>
>> but 4 years later there is still no single in-kernel user for this code?
> 
> There will be, via DRM tree.
> 
> Regards,
> Lukasz
> 
>>
>> Best regards,
>> -- 
>> Bartlomiej Zolnierkiewicz
>> Samsung R&D Institute Poland
>> Samsung Electronics
>>
>>>>>
>>>>>> Also, the devfreq device driver specifies their own
>>>>>> information and data into devfreq_dev_profile structure
>>>>>> before registering the devfreq device with devfreq_add_device().
>>>>>> This patch breaks the basic usage rule of devfreq_dev_profile structure.
>>>>>
>>>>> Well, 'struct devfreq_stats *stats' can be trivially moved out of
>>>>> 'struct devfreq_profile' to 'struct devfreq' if you prefer it that
>>>>> way..
>>>>>
>>>>> Best regards,
>>>>> -- 
>>>>> Bartlomiej Zolnierkiewicz
>>>>> Samsung R&D Institute Poland
>>>>> Samsung Electronics
>>>>>
>>>>>> So, I can't agree this patch. Not ack.
>>>>>>
>>>>>> Regards,
>>>>>> Chanwoo Choi
>>>>>>
>>>>>> On 11/13/19 6:13 PM, Kamil Konieczny wrote:
>>>>>>> Count time and transitions between devfreq frequencies in separate struct
>>>>>>> for improved code readability and maintenance.
>>>>>>>
>>>>>>> Signed-off-by: Kamil Konieczny <[e-mail]>
>>>>>>> ---
>>>>>>>   drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>>>>>>>   drivers/devfreq/exynos-bus.c       |   6 +-
>>>>>>>   drivers/devfreq/governor_passive.c |  26 +++--
>>>>>>>   include/linux/devfreq.h            |  43 ++++----
>>>>>>>   4 files changed, 129 insertions(+), 102 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>>>>> index d79412b0de59..d85867a91230 100644
>>>>>>> --- a/drivers/devfreq/devfreq.c
>>>>>>> +++ b/drivers/devfreq/devfreq.c
>>>>>>> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>>>>>>    */
>>>>>>>   static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>>>   {
>>>>>>> +    struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>>>       int lev;
>>>>>>>   -    for (lev = 0; lev < devfreq->profile->max_state; lev++)
>>>>>>> -        if (freq == devfreq->profile->freq_table[lev])
>>>>>>> +    for (lev = 0; lev < stats->max_state; lev++)
>>>>>>> +        if (freq == stats->freq_table[lev])
>>>>>>>               return lev;
>>>>>>>         return -EINVAL;
>>>>>>> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>>>   static int set_freq_table(struct devfreq *devfreq)
>>>>>>>   {
>>>>>>>       struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>>> +    struct devfreq_stats *stats;
>>>>>>>       struct dev_pm_opp *opp;
>>>>>>>       unsigned long freq;
>>>>>>> -    int i, count;
>>>>>>> +    int i, count, err = -ENOMEM;
>>>>>>>         /* Initialize the freq_table from OPP table */
>>>>>>>       count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>>>>>>>       if (count <= 0)
>>>>>>>           return -EINVAL;
>>>>>>>   -    profile->max_state = count;
>>>>>>> -    profile->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>>>> -                    count,
>>>>>>> -                    sizeof(*profile->freq_table),
>>>>>>> -                    GFP_KERNEL);
>>>>>>> -    if (!profile->freq_table) {
>>>>>>> -        profile->max_state = 0;
>>>>>>> +    stats = devm_kzalloc(devfreq->dev.parent,
>>>>>>> +                 sizeof(struct devfreq_stats), GFP_KERNEL);
>>>>>>> +    if (!stats)
>>>>>>>           return -ENOMEM;
>>>>>>> -    }
>>>>>>>   -    for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
>>>>>>> +    profile->stats = stats;
>>>>>>> +    stats->max_state = count;
>>>>>>> +    stats->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>>>> +                     count,
>>>>>>> +                     sizeof(*stats->freq_table),
>>>>>>> +                     GFP_KERNEL);
>>>>>>> +    if (!stats->freq_table)
>>>>>>> +        goto err_no_mem;
>>>>>>> +
>>>>>>> +    for (i = 0, freq = 0; i < count; i++, freq++) {
>>>>>>>           opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>>>>>>>           if (IS_ERR(opp)) {
>>>>>>> -            devm_kfree(devfreq->dev.parent, profile->freq_table);
>>>>>>> -            profile->max_state = 0;
>>>>>>> -            return PTR_ERR(opp);
>>>>>>> +            devm_kfree(devfreq->dev.parent, stats->freq_table);
>>>>>>> +            stats->max_state = 0;
>>>>>>> +            err = PTR_ERR(opp);
>>>>>>> +            goto err_no_mem;
>>>>>>>           }
>>>>>>>           dev_pm_opp_put(opp);
>>>>>>> -        profile->freq_table[i] = freq;
>>>>>>> +        stats->freq_table[i] = freq;
>>>>>>>       }
>>>>>>>   -    profile->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>>>> -                        array3_size(sizeof(unsigned int),
>>>>>>> -                            count, count),
>>>>>>> -                        GFP_KERNEL);
>>>>>>> -    if (!profile->trans_table)
>>>>>>> +    stats->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>>>> +                      array3_size(sizeof(unsigned int),
>>>>>>> +                              count, count),
>>>>>>> +                      GFP_KERNEL);
>>>>>>> +    if (!stats->trans_table)
>>>>>>>           goto err_no_mem;
>>>>>>>   -    profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>>>> -                          sizeof(*profile->time_in_state),
>>>>>>> -                          GFP_KERNEL);
>>>>>>> -    if (!profile->time_in_state)
>>>>>>> +    stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>>>> +                        sizeof(*stats->time_in_state),
>>>>>>> +                        GFP_KERNEL);
>>>>>>> +    if (!stats->time_in_state)
>>>>>>>           goto err_no_mem;
>>>>>>>   -    profile->last_time = get_jiffies_64();
>>>>>>> -    spin_lock_init(&profile->stats_lock);
>>>>>>> +    stats->last_time = get_jiffies_64();
>>>>>>> +    spin_lock_init(&stats->stats_lock);
>>>>>>>         return 0;
>>>>>>>   err_no_mem:
>>>>>>> -    profile->max_state = 0;
>>>>>>> -    return -ENOMEM;
>>>>>>> +    stats->max_state = 0;
>>>>>>> +    devm_kfree(devfreq->dev.parent, profile->stats);
>>>>>>> +    profile->stats = NULL;
>>>>>>> +    return err;
>>>>>>>   }
>>>>>>>     /**
>>>>>>> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>>>>>>    */
>>>>>>>   int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>>   {
>>>>>>> -    struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>>> +    struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>>>       unsigned long long cur_time;
>>>>>>>       int lev, prev_lev, ret = 0;
>>>>>>>   @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>>         /* Immediately exit if previous_freq is not initialized yet. */
>>>>>>>       if (!devfreq->previous_freq) {
>>>>>>> -        spin_lock(&profile->stats_lock);
>>>>>>> -        profile->last_time = cur_time;
>>>>>>> -        spin_unlock(&profile->stats_lock);
>>>>>>> +        spin_lock(&stats->stats_lock);
>>>>>>> +        stats->last_time = cur_time;
>>>>>>> +        spin_unlock(&stats->stats_lock);
>>>>>>>           return 0;
>>>>>>>       }
>>>>>>>         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>>>>>>>   -    spin_lock(&profile->stats_lock);
>>>>>>> +    spin_lock(&stats->stats_lock);
>>>>>>>       if (prev_lev < 0) {
>>>>>>>           ret = prev_lev;
>>>>>>>           goto out;
>>>>>>>       }
>>>>>>>   -    profile->time_in_state[prev_lev] +=
>>>>>>> -             cur_time - profile->last_time;
>>>>>>> +    stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>>>>>>>       lev = devfreq_get_freq_level(devfreq, freq);
>>>>>>>       if (lev < 0) {
>>>>>>>           ret = lev;
>>>>>>> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>>       }
>>>>>>>         if (lev != prev_lev) {
>>>>>>> -        profile->trans_table[(prev_lev *
>>>>>>> -                profile->max_state) + lev]++;
>>>>>>> -        profile->total_trans++;
>>>>>>> +        stats->trans_table[(prev_lev *
>>>>>>> +                stats->max_state) + lev]++;
>>>>>>> +        stats->total_trans++;
>>>>>>>       }
>>>>>>>     out:
>>>>>>> -    profile->last_time = cur_time;
>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>> +    stats->last_time = cur_time;
>>>>>>> +    spin_unlock(&stats->stats_lock);
>>>>>>>       return ret;
>>>>>>>   }
>>>>>>>   EXPORT_SYMBOL(devfreq_update_status);
>>>>>>> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>>>>>>           queue_delayed_work(devfreq_wq, &devfreq->work,
>>>>>>>               msecs_to_jiffies(profile->polling_ms));
>>>>>>>   -    spin_lock(&profile->stats_lock);
>>>>>>> -    profile->last_time = get_jiffies_64();
>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>> +    spin_lock(&profile->stats->stats_lock);
>>>>>>> +    profile->stats->last_time = get_jiffies_64();
>>>>>>> +    spin_unlock(&profile->stats->stats_lock);
>>>>>>>       devfreq->stop_polling = false;
>>>>>>>         if (profile->get_cur_freq &&
>>>>>>> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>>>>>>       devfreq->data = data;
>>>>>>>       devfreq->nb.notifier_call = devfreq_notifier_call;
>>>>>>>   -    if (!profile->max_state && !profile->freq_table) {
>>>>>>> +    if (!profile->stats) {
>>>>>>>           mutex_unlock(&devfreq->lock);
>>>>>>>           err = set_freq_table(devfreq);
>>>>>>>           if (err < 0)
>>>>>>> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>                     const char *buf, size_t count)
>>>>>>>   {
>>>>>>>       struct devfreq *df = to_devfreq(dev);
>>>>>>> +    struct devfreq_stats *stats = df->profile->stats;
>>>>>>>       unsigned long value;
>>>>>>>       int ret;
>>>>>>>   @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>               goto unlock;
>>>>>>>           }
>>>>>>>       } else {
>>>>>>> -        unsigned long *freq_table = df->profile->freq_table;
>>>>>>> +        unsigned long *freq_table = stats->freq_table;
>>>>>>>             /* Get minimum frequency according to sorting order */
>>>>>>> -        if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>>>> +        if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>>>>               value = freq_table[0];
>>>>>>>           else
>>>>>>> -            value = freq_table[df->profile->max_state - 1];
>>>>>>> +            value = freq_table[stats->max_state - 1];
>>>>>>>       }
>>>>>>>         df->min_freq = value;
>>>>>>> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>                     const char *buf, size_t count)
>>>>>>>   {
>>>>>>>       struct devfreq *df = to_devfreq(dev);
>>>>>>> +    struct devfreq_stats *stats = df->profile->stats;
>>>>>>>       unsigned long value;
>>>>>>>       int ret;
>>>>>>>   @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>               goto unlock;
>>>>>>>           }
>>>>>>>       } else {
>>>>>>> -        unsigned long *freq_table = df->profile->freq_table;
>>>>>>> +        unsigned long *freq_table = stats->freq_table;
>>>>>>>             /* Get maximum frequency according to sorting order */
>>>>>>> -        if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>>>> -            value = freq_table[df->profile->max_state - 1];
>>>>>>> +        if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>>>> +            value = freq_table[stats->max_state - 1];
>>>>>>>           else
>>>>>>>               value = freq_table[0];
>>>>>>>       }
>>>>>>> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>>>>>>>                         char *buf)
>>>>>>>   {
>>>>>>>       struct devfreq *df = to_devfreq(d);
>>>>>>> +    struct devfreq_stats *stats = df->profile->stats;
>>>>>>>       ssize_t count = 0;
>>>>>>>       int i;
>>>>>>>         mutex_lock(&df->lock);
>>>>>>>   -    for (i = 0; i < df->profile->max_state; i++)
>>>>>>> +    for (i = 0; i < stats->max_state; i++)
>>>>>>>           count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
>>>>>>> -                "%lu ", df->profile->freq_table[i]);
>>>>>>> +                "%lu ", stats->freq_table[i]);
>>>>>>>         mutex_unlock(&df->lock);
>>>>>>>       /* Truncate the trailing space */
>>>>>>> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>>>   {
>>>>>>>       struct devfreq *devfreq = to_devfreq(dev);
>>>>>>>       struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>>> +    struct devfreq_stats *stats = profile->stats;
>>>>>>> +    unsigned int max_state = stats->max_state;
>>>>>>>       ssize_t len;
>>>>>>>       int i, j;
>>>>>>> -    unsigned int max_state = profile->max_state;
>>>>>>>         if (!devfreq->stop_polling &&
>>>>>>>               devfreq_update_status(devfreq, devfreq->previous_freq))
>>>>>>> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>>>       len = sprintf(buf, "     From  :   To\n");
>>>>>>>       len += sprintf(buf + len, "           :");
>>>>>>>   -    spin_lock(&profile->stats_lock);
>>>>>>> +    spin_lock(&stats->stats_lock);
>>>>>>>       for (i = 0; i < max_state; i++)
>>>>>>>           len += sprintf(buf + len, "%10lu",
>>>>>>> -                profile->freq_table[i]);
>>>>>>> +                stats->freq_table[i]);
>>>>>>>         len += sprintf(buf + len, "   time(ms)\n");
>>>>>>>         for (i = 0; i < max_state; i++) {
>>>>>>> -        if (profile->freq_table[i] == devfreq->previous_freq)
>>>>>>> +        if (stats->freq_table[i] == devfreq->previous_freq)
>>>>>>>               len += sprintf(buf + len, "*");
>>>>>>>           else
>>>>>>>               len += sprintf(buf + len, " ");
>>>>>>>             len += sprintf(buf + len, "%10lu:",
>>>>>>> -                profile->freq_table[i]);
>>>>>>> +                stats->freq_table[i]);
>>>>>>>           for (j = 0; j < max_state; j++)
>>>>>>>               len += sprintf(buf + len, "%10u",
>>>>>>> -                profile->trans_table[(i * max_state) + j]);
>>>>>>> +                stats->trans_table[(i * max_state) + j]);
>>>>>>>           len += sprintf(buf + len, "%10llu\n", (u64)
>>>>>>> -            jiffies64_to_msecs(profile->time_in_state[i]));
>>>>>>> +            jiffies64_to_msecs(stats->time_in_state[i]));
>>>>>>>       }
>>>>>>>         len += sprintf(buf + len, "Total transition : %u\n",
>>>>>>> -                    profile->total_trans);
>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>> +                    stats->total_trans);
>>>>>>> +    spin_unlock(&stats->stats_lock);
>>>>>>>       return len;
>>>>>>>   }
>>>>>>>   static DEVICE_ATTR_RO(trans_stat);
>>>>>>>   -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
>>>>>>> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>>>>>>>   {
>>>>>>> -    unsigned int count = profile->max_state;
>>>>>>> -
>>>>>>> -    spin_lock(&profile->stats_lock);
>>>>>>> -    memset(profile->time_in_state, 0, count * sizeof(u64));
>>>>>>> -    memset(profile->trans_table, 0, count * count * sizeof(int));
>>>>>>> -    profile->last_time = get_jiffies_64();
>>>>>>> -    profile->total_trans = 0;
>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>> +    unsigned int count = stats->max_state;
>>>>>>> +
>>>>>>> +    spin_lock(&stats->stats_lock);
>>>>>>> +    memset(stats->time_in_state, 0, count * sizeof(u64));
>>>>>>> +    memset(stats->trans_table, 0, count * count * sizeof(int));
>>>>>>> +    stats->last_time = get_jiffies_64();
>>>>>>> +    stats->total_trans = 0;
>>>>>>> +    spin_unlock(&stats->stats_lock);
>>>>>>>   }
>>>>>>>     static ssize_t trans_reset_store(struct device *dev,
>>>>>>> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>>>>>>>   {
>>>>>>>       struct devfreq *devfreq = to_devfreq(dev);
>>>>>>>   -    defvreq_stats_clear_table(devfreq->profile);
>>>>>>> +    defvreq_stats_clear_table(devfreq->profile->stats);
>>>>>>>         return count;
>>>>>>>   }
>>>>>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>>>>>> index d9f377912c10..b212aae2bb3e 100644
>>>>>>> --- a/drivers/devfreq/exynos-bus.c
>>>>>>> +++ b/drivers/devfreq/exynos-bus.c
>>>>>>> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>>>>>       }
>>>>>>>     out:
>>>>>>> -    max_state = bus->devfreq->profile->max_state;
>>>>>>> -    min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>>>>>>> -    max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>>>>>>> +    max_state = profile->stats->max_state;
>>>>>>> +    min_freq = (profile->stats->freq_table[0] / 1000);
>>>>>>> +    max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>>>>>>>       pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>>>>>>>               dev_name(dev), min_freq, max_freq);
>>>>>>>   diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>>>>>>> index 58308948b863..b2d87a88335c 100644
>>>>>>> --- a/drivers/devfreq/governor_passive.c
>>>>>>> +++ b/drivers/devfreq/governor_passive.c
>>>>>>> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>>       struct devfreq_passive_data *p_data
>>>>>>>               = (struct devfreq_passive_data *)devfreq->data;
>>>>>>>       struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>>>>>>> +    struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
>>>>>>> +    struct devfreq_stats *stats;
>>>>>>>       unsigned long child_freq = ULONG_MAX;
>>>>>>>       struct dev_pm_opp *opp;
>>>>>>>       int i, count, ret = 0;
>>>>>>> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>>        * device. And then the index is used for getting the suitable
>>>>>>>        * new frequency for passive devfreq device.
>>>>>>>        */
>>>>>>> -    if (!devfreq->profile || !devfreq->profile->freq_table
>>>>>>> -        || devfreq->profile->max_state <= 0)
>>>>>>> +    if (!devfreq->profile || !devfreq->profile->stats ||
>>>>>>> +        devfreq->profile->stats->max_state <= 0 ||
>>>>>>> +        !parent_devfreq->profile ||    !parent_devfreq->profile->stats ||
>>>>>>> +        parent_devfreq->profile->stats->max_state <= 0)
>>>>>>>           return -EINVAL;
>>>>>>>   +    stats = devfreq->profile->stats;
>>>>>>> +    parent_stats = parent_devfreq->profile->stats;
>>>>>>>       /*
>>>>>>>        * The passive governor have to get the correct frequency from OPP
>>>>>>>        * list of parent device. Because in this case, *freq is temporary
>>>>>>> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>>        * Get the OPP table's index of decided freqeuncy by governor
>>>>>>>        * of parent device.
>>>>>>>        */
>>>>>>> -    for (i = 0; i < parent_devfreq->profile->max_state; i++)
>>>>>>> -        if (parent_devfreq->profile->freq_table[i] == *freq)
>>>>>>> +    for (i = 0; i < parent_stats->max_state; i++)
>>>>>>> +        if (parent_stats->freq_table[i] == *freq)
>>>>>>>               break;
>>>>>>>   -    if (i == parent_devfreq->profile->max_state) {
>>>>>>> +    if (i == parent_stats->max_state) {
>>>>>>>           ret = -EINVAL;
>>>>>>>           goto out;
>>>>>>>       }
>>>>>>>         /* Get the suitable frequency by using index of parent device. */
>>>>>>> -    if (i < devfreq->profile->max_state) {
>>>>>>> -        child_freq = devfreq->profile->freq_table[i];
>>>>>>> +    if (i < stats->max_state) {
>>>>>>> +        child_freq = stats->freq_table[i];
>>>>>>>       } else {
>>>>>>> -        count = devfreq->profile->max_state;
>>>>>>> -        child_freq = devfreq->profile->freq_table[count - 1];
>>>>>>> +        count = stats->max_state;
>>>>>>> +        child_freq = stats->freq_table[count - 1];
>>>>>>>       }
>>>>>>>         /* Return the suitable frequency for passive device. */
>>>>>>> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>>>>>>>       if (ret < 0)
>>>>>>>           goto out;
>>>>>>>   -    if (devfreq->profile->freq_table
>>>>>>> +    if (devfreq->profile->stats
>>>>>>>           && (devfreq_update_status(devfreq, freq)))
>>>>>>>           dev_err(&devfreq->dev,
>>>>>>>               "Couldn't update frequency transition information.\n");
>>>>>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>>>>>> index 4ceb2a517a9c..8459af1a1583 100644
>>>>>>> --- a/include/linux/devfreq.h
>>>>>>> +++ b/include/linux/devfreq.h
>>>>>>> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>>>>>>>    */
>>>>>>>   #define DEVFREQ_FLAG_LEAST_UPPER_BOUND        0x1
>>>>>>>   +/**
>>>>>>> + * struct devfreq_stats - Devfreq's transitions stats counters
>>>>>>> + * @freq_table:        Optional list of frequencies to support statistics
>>>>>>> + *            and freq_table must be generated in ascending order.
>>>>>>> + * @max_state:        The size of freq_table.
>>>>>>> + * @total_trans:    Number of devfreq transitions
>>>>>>> + * @trans_table:    Statistics of devfreq transitions
>>>>>>> + * @time_in_state:    Statistics of devfreq states
>>>>>>> + * @last_time:        The last time stats were updated
>>>>>>> + * @stats_lock:        Lock protecting trans_table, time_in_state,
>>>>>>> + *            last_time and total_trans used for statistics
>>>>>>> + */
>>>>>>> +struct devfreq_stats {
>>>>>>> +    unsigned long *freq_table;
>>>>>>> +    unsigned int max_state;
>>>>>>> +
>>>>>>> +    /* information for device frequency transition */
>>>>>>> +    unsigned int total_trans;
>>>>>>> +    unsigned int *trans_table;
>>>>>>> +    u64 *time_in_state;
>>>>>>> +    unsigned long long last_time;
>>>>>>> +    spinlock_t stats_lock;
>>>>>>> +};
>>>>>>> +
>>>>>>>   /**
>>>>>>>    * struct devfreq_dev_profile - Devfreq's user device profile
>>>>>>>    * @initial_freq:    The operating frequency when devfreq_add_device() is
>>>>>>> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>>>>>>>    *            from devfreq_remove_device() call. If the user
>>>>>>>    *            has registered devfreq->nb at a notifier-head,
>>>>>>>    *            this is the time to unregister it.
>>>>>>> - * @freq_table:        Optional list of frequencies to support statistics
>>>>>>> - *            and freq_table must be generated in ascending order.
>>>>>>> - * @max_state:        The size of freq_table.
>>>>>>> - * @total_trans:    Number of devfreq transitions
>>>>>>> - * @trans_table:    Statistics of devfreq transitions
>>>>>>> - * @time_in_state:    Statistics of devfreq states
>>>>>>> - * @last_time:        The last time stats were updated
>>>>>>> - * @stats_lock:        Lock protecting trans_table, time_in_state,
>>>>>>> - *            last_time and total_trans used for statistics
>>>>>>> + * @stats:        Statistics of devfreq states and state transitions
>>>>>>>    */
>>>>>>>   struct devfreq_dev_profile {
>>>>>>>       unsigned long initial_freq;
>>>>>>> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>>>>>>>       int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>>>>>>>       void (*exit)(struct device *dev);
>>>>>>>   -    unsigned long *freq_table;
>>>>>>> -    unsigned int max_state;
>>>>>>> -    /* information for device frequency transition */
>>>>>>> -    unsigned int total_trans;
>>>>>>> -    unsigned int *trans_table;
>>>>>>> -    u64 *time_in_state;
>>>>>>> -    unsigned long long last_time;
>>>>>>> -    spinlock_t stats_lock;
>>>>>>> +    struct devfreq_stats *stats;
>>>>>>>   };
>>>>>>>     /**
>>>>>>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> [e-mail]
>> https://protect2.fireeye.com/url?k=856913bb-d8f2efd8-856898f4-0cc47a31cdbc-5cb40ce5f31ed8ed&u=http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
> 
>

Lukasz Luba Dec. 17, 2019, 9:10 a.m. UTC | #8

Hi Chanwoo,

On 12/17/19 12:07 AM, Chanwoo Choi wrote:
> Hi Lukaz,
> 
> On 12/16/19 10:01 PM, Lukasz Luba wrote:
>> Hi Bartek,
>>
>> [added Dietmar, Robin, Andrzej (for upcoming DRM drm-misc-next)]
>>
>> On 11/15/19 12:40 PM, Bartlomiej Zolnierkiewicz wrote:
>>>
>>> [ added Zhang, Eduardo, Ørjan and Javi to Cc: ]
>>>
>>> On 11/15/19 7:21 AM, Chanwoo Choi wrote:
>>>> Hi Bartlomiej,
>>>>
>>>> On 11/15/19 12:25 PM, Chanwoo Choi wrote:
>>>>> Hi Bartlomiej,
>>>>>
>>>>> On 11/15/19 3:01 AM, Bartlomiej Zolnierkiewicz wrote:
>>>>>>
>>>>>> Hi Chanwoo,
>>>>>>
>>>>>> On 11/14/19 2:52 AM, Chanwoo Choi wrote:
>>>>>>> Hi Kamil,
>>>>>>>
>>>>>>> The 'freq_table' and 'max_state' in the devfreq_dev_profile
>>>>>>> were used in the ARM Mali device driver[1][2][3]. Although ARM Mali
>>>>>>> device driver was posted to mainline kernel, they used
>>>>>>> them for a long time. It means that this patch break
>>>>>>> the compatibility. The ARM Mali drivers are very
>>>>>>> important devfreq device driver.
>>>>>>
>>>>>> This argument is not a a technical one and the official upstream
>>>>>> kernel policy is to not depend on out-of-tree drivers.
>>>>>>
>>>>>> Besides the ARM Mali drivers are full of code like:
>>>>>>
>>>>>> #if LINUX_VERSION_CODE >= KERNEL_VERSION(x, y, z)
>>>>>> ...
>>>>>> #else
>>>>>> ...
>>>>>> #endif
>>>>>>
>>>>>> so few more instances of similar code won't do any harm.. ;-)
>>>>>>
>>>>>>> [1] https://protect2.fireeye.com/url?k=909caa5c-cd52abe8-909d2113-000babdfecba-812f16576c3614a3&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/bifrost-kernel#
>>>>>>> [2] https://protect2.fireeye.com/url?k=33265f96-6ee85e22-3327d4d9-000babdfecba-44c2daec328712e6&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/midgard-kernel
>>>>>>> [3] https://protect2.fireeye.com/url?k=69bdcab0-3473cb04-69bc41ff-000babdfecba-4b576facf85e0208&u=https://developer.arm.com/tools-and-software/graphics-and-gaming/mali-drivers/utgard-kernel
>>>>>>
>>>>>> I took a look at ARM Mali drivers source code anyway and I fail to
>>>>>> see a rationale behind their behavior of doing 'freq_table' and
>>>>>> 'max_state' initialization in the driver itself (instead of leaving
>>>>>> it up to the devfreq core code, like all in-kernel drivers are doing
>>>>>> already).
>>>>>>
>>>>>> Could you please explain rationale behind ARM Mali drivers' special
>>>>>> needs?
>>>>>>
>>>>>> [ Both ARM Mali and devfreq core code are using generic PM OPP code
>>>>>>     these days to do 'freq_table' and 'max_state' initialization, the
>>>>>>     only difference seems to be that ARM Mali creates the frequency
>>>>>>     table in the descending order (but there also seems to be no real
>>>>>>     need for it). ]
>>>>>>
>>>>>> Maybe this is an opportunity to simplify also the ARM Mali driver?
>>>>>
>>>>> OK. I agree to simplify them on this time.
>>>>> For touching the 'freq_table' and 'max_state', need to fix
>>>>> the descending order of freq_table.
>>>>>
>>>>> The partition_enable_ops() in the drivers/thermal/devfreq_cooling.c
>>>>> requires the descending order of freq_table. Have to change it by using
>>>>> the ascending time or support both ascending and descending order for freq_table.
>>>>>
>>>>> 1. Move freq_table, max_state of devfreq_dev_profile to struct devfreq
>>>>> 2. Edit partition_enable_ops() in the drivers/thermal/devfreq_cooling.c
>>>>>      by using ascending order instead of descending order.
>>>>>
>>>>
>>>> After changed about 'freq_table' and 'max_state', the build error
>>>> will happen on ARM mail driver because the initialization code of
>>>> 'freq_table' in ARM mali driver, didn't check the kernel version.
>>>>
>>>> The first devfreq patch provided the 'freq_table' as optional variable
>>>> in the 'struct devfreq_dev_profile'. Even if ARM mali driver is out of mainline tree,
>>>> this change seems that break the usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
>>>>
>>>> So, if there are no any beneficial reason, I just keep the current status of 'freq_table'
>>>> in order to keep the previous usage rule of 'freq_table' in 'struct devfreq_dev_profile'.
>>>>
>>>> Frankly, I'm note sure that it is necessary. I don't want to make
>>>> the side-effect without any useful reason.
>>>>
>>>> But,
>>>> Separately, have to fix the ordering issue of partition_enable_ops()
>>>> in the drivers/thermal/devfreq_cooling.c.
>>>
>>> Hmmm.. fixing partition_enable_opps() should be trivial but I wonder
>>> why we are carrying devfreq_cooling.c code in upstream kernel at all?
>>
>> Well, the devfreq_cooling.c is going to have a client in mainline:
>> the GPU driver - Panfrost.
>>
>> It is already in DRM branch 'drm-misc-next':
>> https://protect2.fireeye.com/url?k=75a0e087-283b1ce4-75a16bc8-0cc47a31cdbc-4953aa9e0574f6dc&u=https://patchwork.freedesktop.org/patch/342848/
>>
>> Regarding the devfreq_cooling.c code structure.
>> I am currently working on cleaning up the devfreq cooling code and
>> adding Energy Model instead for private freq, power tables. It will be
>> in similar fashion as it is done in cpufreq_cooling. The model will
>> be also simplified so hopefully more clients would come.
>> It is under internal review and will be posted shortly.
> 
> Good news about Energy Model. When you send the patch related to Energy model,
> please add me to Cc list.

I will add you, thanks. More eyeballs in capturing bugs are more than
welcome.

Regards,
Lukasz

> 
>>
>>>
>>> It has been merged in the following commit:
>>>
>>> commit a76caf55e5b356ba20a5a43ac4d9f7a04b20941d
>>> Author: Ørjan Eide <[e-mail]>
>>> Date:   Thu Sep 10 18:09:30 2015 +0100
>>>
>>>       thermal: Add devfreq cooling
>>>            Add a generic thermal cooling device for devfreq, that is similar to
>>>       cpu_cooling.
>>>            The device must use devfreq.  In order to use the power extension of the
>>>       cooling device, it must have registered its OPPs using the OPP library.
>>>            Cc: Zhang Rui <[e-mail]>
>>>       Cc: Eduardo Valentin <[e-mail]>
>>>       Signed-off-by: Javi Merino <[e-mail]>
>>>       Signed-off-by: Ørjan Eide <[e-mail]>
>>>       Signed-off-by: Eduardo Valentin <[e-mail]>
>>> ...
>>>
>>> but 4 years later there is still no single in-kernel user for this code?
>>
>> There will be, via DRM tree.
>>
>> Regards,
>> Lukasz
>>
>>>
>>> Best regards,
>>> -- 
>>> Bartlomiej Zolnierkiewicz
>>> Samsung R&D Institute Poland
>>> Samsung Electronics
>>>
>>>>>>
>>>>>>> Also, the devfreq device driver specifies their own
>>>>>>> information and data into devfreq_dev_profile structure
>>>>>>> before registering the devfreq device with devfreq_add_device().
>>>>>>> This patch breaks the basic usage rule of devfreq_dev_profile structure.
>>>>>>
>>>>>> Well, 'struct devfreq_stats *stats' can be trivially moved out of
>>>>>> 'struct devfreq_profile' to 'struct devfreq' if you prefer it that
>>>>>> way..
>>>>>>
>>>>>> Best regards,
>>>>>> -- 
>>>>>> Bartlomiej Zolnierkiewicz
>>>>>> Samsung R&D Institute Poland
>>>>>> Samsung Electronics
>>>>>>
>>>>>>> So, I can't agree this patch. Not ack.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Chanwoo Choi
>>>>>>>
>>>>>>> On 11/13/19 6:13 PM, Kamil Konieczny wrote:
>>>>>>>> Count time and transitions between devfreq frequencies in separate struct
>>>>>>>> for improved code readability and maintenance.
>>>>>>>>
>>>>>>>> Signed-off-by: Kamil Konieczny <[e-mail]>
>>>>>>>> ---
>>>>>>>>    drivers/devfreq/devfreq.c          | 156 ++++++++++++++++-------------
>>>>>>>>    drivers/devfreq/exynos-bus.c       |   6 +-
>>>>>>>>    drivers/devfreq/governor_passive.c |  26 +++--
>>>>>>>>    include/linux/devfreq.h            |  43 ++++----
>>>>>>>>    4 files changed, 129 insertions(+), 102 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>>>>>> index d79412b0de59..d85867a91230 100644
>>>>>>>> --- a/drivers/devfreq/devfreq.c
>>>>>>>> +++ b/drivers/devfreq/devfreq.c
>>>>>>>> @@ -105,10 +105,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>>>>>>>     */
>>>>>>>>    static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>>>>    {
>>>>>>>> +    struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>>>>        int lev;
>>>>>>>>    -    for (lev = 0; lev < devfreq->profile->max_state; lev++)
>>>>>>>> -        if (freq == devfreq->profile->freq_table[lev])
>>>>>>>> +    for (lev = 0; lev < stats->max_state; lev++)
>>>>>>>> +        if (freq == stats->freq_table[lev])
>>>>>>>>                return lev;
>>>>>>>>          return -EINVAL;
>>>>>>>> @@ -117,56 +118,64 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
>>>>>>>>    static int set_freq_table(struct devfreq *devfreq)
>>>>>>>>    {
>>>>>>>>        struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>>>> +    struct devfreq_stats *stats;
>>>>>>>>        struct dev_pm_opp *opp;
>>>>>>>>        unsigned long freq;
>>>>>>>> -    int i, count;
>>>>>>>> +    int i, count, err = -ENOMEM;
>>>>>>>>          /* Initialize the freq_table from OPP table */
>>>>>>>>        count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
>>>>>>>>        if (count <= 0)
>>>>>>>>            return -EINVAL;
>>>>>>>>    -    profile->max_state = count;
>>>>>>>> -    profile->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>>>>> -                    count,
>>>>>>>> -                    sizeof(*profile->freq_table),
>>>>>>>> -                    GFP_KERNEL);
>>>>>>>> -    if (!profile->freq_table) {
>>>>>>>> -        profile->max_state = 0;
>>>>>>>> +    stats = devm_kzalloc(devfreq->dev.parent,
>>>>>>>> +                 sizeof(struct devfreq_stats), GFP_KERNEL);
>>>>>>>> +    if (!stats)
>>>>>>>>            return -ENOMEM;
>>>>>>>> -    }
>>>>>>>>    -    for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
>>>>>>>> +    profile->stats = stats;
>>>>>>>> +    stats->max_state = count;
>>>>>>>> +    stats->freq_table = devm_kcalloc(devfreq->dev.parent,
>>>>>>>> +                     count,
>>>>>>>> +                     sizeof(*stats->freq_table),
>>>>>>>> +                     GFP_KERNEL);
>>>>>>>> +    if (!stats->freq_table)
>>>>>>>> +        goto err_no_mem;
>>>>>>>> +
>>>>>>>> +    for (i = 0, freq = 0; i < count; i++, freq++) {
>>>>>>>>            opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
>>>>>>>>            if (IS_ERR(opp)) {
>>>>>>>> -            devm_kfree(devfreq->dev.parent, profile->freq_table);
>>>>>>>> -            profile->max_state = 0;
>>>>>>>> -            return PTR_ERR(opp);
>>>>>>>> +            devm_kfree(devfreq->dev.parent, stats->freq_table);
>>>>>>>> +            stats->max_state = 0;
>>>>>>>> +            err = PTR_ERR(opp);
>>>>>>>> +            goto err_no_mem;
>>>>>>>>            }
>>>>>>>>            dev_pm_opp_put(opp);
>>>>>>>> -        profile->freq_table[i] = freq;
>>>>>>>> +        stats->freq_table[i] = freq;
>>>>>>>>        }
>>>>>>>>    -    profile->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>>>>> -                        array3_size(sizeof(unsigned int),
>>>>>>>> -                            count, count),
>>>>>>>> -                        GFP_KERNEL);
>>>>>>>> -    if (!profile->trans_table)
>>>>>>>> +    stats->trans_table = devm_kzalloc(devfreq->dev.parent,
>>>>>>>> +                      array3_size(sizeof(unsigned int),
>>>>>>>> +                              count, count),
>>>>>>>> +                      GFP_KERNEL);
>>>>>>>> +    if (!stats->trans_table)
>>>>>>>>            goto err_no_mem;
>>>>>>>>    -    profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>>>>> -                          sizeof(*profile->time_in_state),
>>>>>>>> -                          GFP_KERNEL);
>>>>>>>> -    if (!profile->time_in_state)
>>>>>>>> +    stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
>>>>>>>> +                        sizeof(*stats->time_in_state),
>>>>>>>> +                        GFP_KERNEL);
>>>>>>>> +    if (!stats->time_in_state)
>>>>>>>>            goto err_no_mem;
>>>>>>>>    -    profile->last_time = get_jiffies_64();
>>>>>>>> -    spin_lock_init(&profile->stats_lock);
>>>>>>>> +    stats->last_time = get_jiffies_64();
>>>>>>>> +    spin_lock_init(&stats->stats_lock);
>>>>>>>>          return 0;
>>>>>>>>    err_no_mem:
>>>>>>>> -    profile->max_state = 0;
>>>>>>>> -    return -ENOMEM;
>>>>>>>> +    stats->max_state = 0;
>>>>>>>> +    devm_kfree(devfreq->dev.parent, profile->stats);
>>>>>>>> +    profile->stats = NULL;
>>>>>>>> +    return err;
>>>>>>>>    }
>>>>>>>>      /**
>>>>>>>> @@ -176,7 +185,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>>>>>>>     */
>>>>>>>>    int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>>>    {
>>>>>>>> -    struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>>>> +    struct devfreq_stats *stats = devfreq->profile->stats;
>>>>>>>>        unsigned long long cur_time;
>>>>>>>>        int lev, prev_lev, ret = 0;
>>>>>>>>    @@ -184,22 +193,21 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>>>          /* Immediately exit if previous_freq is not initialized yet. */
>>>>>>>>        if (!devfreq->previous_freq) {
>>>>>>>> -        spin_lock(&profile->stats_lock);
>>>>>>>> -        profile->last_time = cur_time;
>>>>>>>> -        spin_unlock(&profile->stats_lock);
>>>>>>>> +        spin_lock(&stats->stats_lock);
>>>>>>>> +        stats->last_time = cur_time;
>>>>>>>> +        spin_unlock(&stats->stats_lock);
>>>>>>>>            return 0;
>>>>>>>>        }
>>>>>>>>          prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
>>>>>>>>    -    spin_lock(&profile->stats_lock);
>>>>>>>> +    spin_lock(&stats->stats_lock);
>>>>>>>>        if (prev_lev < 0) {
>>>>>>>>            ret = prev_lev;
>>>>>>>>            goto out;
>>>>>>>>        }
>>>>>>>>    -    profile->time_in_state[prev_lev] +=
>>>>>>>> -             cur_time - profile->last_time;
>>>>>>>> +    stats->time_in_state[prev_lev] += cur_time - stats->last_time;
>>>>>>>>        lev = devfreq_get_freq_level(devfreq, freq);
>>>>>>>>        if (lev < 0) {
>>>>>>>>            ret = lev;
>>>>>>>> @@ -207,14 +215,14 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>>>>>>>        }
>>>>>>>>          if (lev != prev_lev) {
>>>>>>>> -        profile->trans_table[(prev_lev *
>>>>>>>> -                profile->max_state) + lev]++;
>>>>>>>> -        profile->total_trans++;
>>>>>>>> +        stats->trans_table[(prev_lev *
>>>>>>>> +                stats->max_state) + lev]++;
>>>>>>>> +        stats->total_trans++;
>>>>>>>>        }
>>>>>>>>      out:
>>>>>>>> -    profile->last_time = cur_time;
>>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>>> +    stats->last_time = cur_time;
>>>>>>>> +    spin_unlock(&stats->stats_lock);
>>>>>>>>        return ret;
>>>>>>>>    }
>>>>>>>>    EXPORT_SYMBOL(devfreq_update_status);
>>>>>>>> @@ -504,9 +512,9 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>>>>>>>            queue_delayed_work(devfreq_wq, &devfreq->work,
>>>>>>>>                msecs_to_jiffies(profile->polling_ms));
>>>>>>>>    -    spin_lock(&profile->stats_lock);
>>>>>>>> -    profile->last_time = get_jiffies_64();
>>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>>> +    spin_lock(&profile->stats->stats_lock);
>>>>>>>> +    profile->stats->last_time = get_jiffies_64();
>>>>>>>> +    spin_unlock(&profile->stats->stats_lock);
>>>>>>>>        devfreq->stop_polling = false;
>>>>>>>>          if (profile->get_cur_freq &&
>>>>>>>> @@ -677,7 +685,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>>>>>>>        devfreq->data = data;
>>>>>>>>        devfreq->nb.notifier_call = devfreq_notifier_call;
>>>>>>>>    -    if (!profile->max_state && !profile->freq_table) {
>>>>>>>> +    if (!profile->stats) {
>>>>>>>>            mutex_unlock(&devfreq->lock);
>>>>>>>>            err = set_freq_table(devfreq);
>>>>>>>>            if (err < 0)
>>>>>>>> @@ -1282,6 +1290,7 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>>                      const char *buf, size_t count)
>>>>>>>>    {
>>>>>>>>        struct devfreq *df = to_devfreq(dev);
>>>>>>>> +    struct devfreq_stats *stats = df->profile->stats;
>>>>>>>>        unsigned long value;
>>>>>>>>        int ret;
>>>>>>>>    @@ -1297,13 +1306,13 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>>                goto unlock;
>>>>>>>>            }
>>>>>>>>        } else {
>>>>>>>> -        unsigned long *freq_table = df->profile->freq_table;
>>>>>>>> +        unsigned long *freq_table = stats->freq_table;
>>>>>>>>              /* Get minimum frequency according to sorting order */
>>>>>>>> -        if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>>>>> +        if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>>>>>                value = freq_table[0];
>>>>>>>>            else
>>>>>>>> -            value = freq_table[df->profile->max_state - 1];
>>>>>>>> +            value = freq_table[stats->max_state - 1];
>>>>>>>>        }
>>>>>>>>          df->min_freq = value;
>>>>>>>> @@ -1326,6 +1335,7 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>>                      const char *buf, size_t count)
>>>>>>>>    {
>>>>>>>>        struct devfreq *df = to_devfreq(dev);
>>>>>>>> +    struct devfreq_stats *stats = df->profile->stats;
>>>>>>>>        unsigned long value;
>>>>>>>>        int ret;
>>>>>>>>    @@ -1341,11 +1351,11 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>>>>>>>>                goto unlock;
>>>>>>>>            }
>>>>>>>>        } else {
>>>>>>>> -        unsigned long *freq_table = df->profile->freq_table;
>>>>>>>> +        unsigned long *freq_table = stats->freq_table;
>>>>>>>>              /* Get maximum frequency according to sorting order */
>>>>>>>> -        if (freq_table[0] < freq_table[df->profile->max_state - 1])
>>>>>>>> -            value = freq_table[df->profile->max_state - 1];
>>>>>>>> +        if (freq_table[0] < freq_table[stats->max_state - 1])
>>>>>>>> +            value = freq_table[stats->max_state - 1];
>>>>>>>>            else
>>>>>>>>                value = freq_table[0];
>>>>>>>>        }
>>>>>>>> @@ -1373,14 +1383,15 @@ static ssize_t available_frequencies_show(struct device *d,
>>>>>>>>                          char *buf)
>>>>>>>>    {
>>>>>>>>        struct devfreq *df = to_devfreq(d);
>>>>>>>> +    struct devfreq_stats *stats = df->profile->stats;
>>>>>>>>        ssize_t count = 0;
>>>>>>>>        int i;
>>>>>>>>          mutex_lock(&df->lock);
>>>>>>>>    -    for (i = 0; i < df->profile->max_state; i++)
>>>>>>>> +    for (i = 0; i < stats->max_state; i++)
>>>>>>>>            count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
>>>>>>>> -                "%lu ", df->profile->freq_table[i]);
>>>>>>>> +                "%lu ", stats->freq_table[i]);
>>>>>>>>          mutex_unlock(&df->lock);
>>>>>>>>        /* Truncate the trailing space */
>>>>>>>> @@ -1398,9 +1409,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>>>>    {
>>>>>>>>        struct devfreq *devfreq = to_devfreq(dev);
>>>>>>>>        struct devfreq_dev_profile *profile = devfreq->profile;
>>>>>>>> +    struct devfreq_stats *stats = profile->stats;
>>>>>>>> +    unsigned int max_state = stats->max_state;
>>>>>>>>        ssize_t len;
>>>>>>>>        int i, j;
>>>>>>>> -    unsigned int max_state = profile->max_state;
>>>>>>>>          if (!devfreq->stop_polling &&
>>>>>>>>                devfreq_update_status(devfreq, devfreq->previous_freq))
>>>>>>>> @@ -1411,45 +1423,45 @@ static ssize_t trans_stat_show(struct device *dev,
>>>>>>>>        len = sprintf(buf, "     From  :   To\n");
>>>>>>>>        len += sprintf(buf + len, "           :");
>>>>>>>>    -    spin_lock(&profile->stats_lock);
>>>>>>>> +    spin_lock(&stats->stats_lock);
>>>>>>>>        for (i = 0; i < max_state; i++)
>>>>>>>>            len += sprintf(buf + len, "%10lu",
>>>>>>>> -                profile->freq_table[i]);
>>>>>>>> +                stats->freq_table[i]);
>>>>>>>>          len += sprintf(buf + len, "   time(ms)\n");
>>>>>>>>          for (i = 0; i < max_state; i++) {
>>>>>>>> -        if (profile->freq_table[i] == devfreq->previous_freq)
>>>>>>>> +        if (stats->freq_table[i] == devfreq->previous_freq)
>>>>>>>>                len += sprintf(buf + len, "*");
>>>>>>>>            else
>>>>>>>>                len += sprintf(buf + len, " ");
>>>>>>>>              len += sprintf(buf + len, "%10lu:",
>>>>>>>> -                profile->freq_table[i]);
>>>>>>>> +                stats->freq_table[i]);
>>>>>>>>            for (j = 0; j < max_state; j++)
>>>>>>>>                len += sprintf(buf + len, "%10u",
>>>>>>>> -                profile->trans_table[(i * max_state) + j]);
>>>>>>>> +                stats->trans_table[(i * max_state) + j]);
>>>>>>>>            len += sprintf(buf + len, "%10llu\n", (u64)
>>>>>>>> -            jiffies64_to_msecs(profile->time_in_state[i]));
>>>>>>>> +            jiffies64_to_msecs(stats->time_in_state[i]));
>>>>>>>>        }
>>>>>>>>          len += sprintf(buf + len, "Total transition : %u\n",
>>>>>>>> -                    profile->total_trans);
>>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>>> +                    stats->total_trans);
>>>>>>>> +    spin_unlock(&stats->stats_lock);
>>>>>>>>        return len;
>>>>>>>>    }
>>>>>>>>    static DEVICE_ATTR_RO(trans_stat);
>>>>>>>>    -static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
>>>>>>>> +static void defvreq_stats_clear_table(struct devfreq_stats *stats)
>>>>>>>>    {
>>>>>>>> -    unsigned int count = profile->max_state;
>>>>>>>> -
>>>>>>>> -    spin_lock(&profile->stats_lock);
>>>>>>>> -    memset(profile->time_in_state, 0, count * sizeof(u64));
>>>>>>>> -    memset(profile->trans_table, 0, count * count * sizeof(int));
>>>>>>>> -    profile->last_time = get_jiffies_64();
>>>>>>>> -    profile->total_trans = 0;
>>>>>>>> -    spin_unlock(&profile->stats_lock);
>>>>>>>> +    unsigned int count = stats->max_state;
>>>>>>>> +
>>>>>>>> +    spin_lock(&stats->stats_lock);
>>>>>>>> +    memset(stats->time_in_state, 0, count * sizeof(u64));
>>>>>>>> +    memset(stats->trans_table, 0, count * count * sizeof(int));
>>>>>>>> +    stats->last_time = get_jiffies_64();
>>>>>>>> +    stats->total_trans = 0;
>>>>>>>> +    spin_unlock(&stats->stats_lock);
>>>>>>>>    }
>>>>>>>>      static ssize_t trans_reset_store(struct device *dev,
>>>>>>>> @@ -1459,7 +1471,7 @@ static ssize_t trans_reset_store(struct device *dev,
>>>>>>>>    {
>>>>>>>>        struct devfreq *devfreq = to_devfreq(dev);
>>>>>>>>    -    defvreq_stats_clear_table(devfreq->profile);
>>>>>>>> +    defvreq_stats_clear_table(devfreq->profile->stats);
>>>>>>>>          return count;
>>>>>>>>    }
>>>>>>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>>>>>>> index d9f377912c10..b212aae2bb3e 100644
>>>>>>>> --- a/drivers/devfreq/exynos-bus.c
>>>>>>>> +++ b/drivers/devfreq/exynos-bus.c
>>>>>>>> @@ -496,9 +496,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>>>>>>        }
>>>>>>>>      out:
>>>>>>>> -    max_state = bus->devfreq->profile->max_state;
>>>>>>>> -    min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
>>>>>>>> -    max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
>>>>>>>> +    max_state = profile->stats->max_state;
>>>>>>>> +    min_freq = (profile->stats->freq_table[0] / 1000);
>>>>>>>> +    max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
>>>>>>>>        pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
>>>>>>>>                dev_name(dev), min_freq, max_freq);
>>>>>>>>    diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>>>>>>>> index 58308948b863..b2d87a88335c 100644
>>>>>>>> --- a/drivers/devfreq/governor_passive.c
>>>>>>>> +++ b/drivers/devfreq/governor_passive.c
>>>>>>>> @@ -18,6 +18,8 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>>>        struct devfreq_passive_data *p_data
>>>>>>>>                = (struct devfreq_passive_data *)devfreq->data;
>>>>>>>>        struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>>>>>>>> +    struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
>>>>>>>> +    struct devfreq_stats *stats;
>>>>>>>>        unsigned long child_freq = ULONG_MAX;
>>>>>>>>        struct dev_pm_opp *opp;
>>>>>>>>        int i, count, ret = 0;
>>>>>>>> @@ -47,10 +49,14 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>>>         * device. And then the index is used for getting the suitable
>>>>>>>>         * new frequency for passive devfreq device.
>>>>>>>>         */
>>>>>>>> -    if (!devfreq->profile || !devfreq->profile->freq_table
>>>>>>>> -        || devfreq->profile->max_state <= 0)
>>>>>>>> +    if (!devfreq->profile || !devfreq->profile->stats ||
>>>>>>>> +        devfreq->profile->stats->max_state <= 0 ||
>>>>>>>> +        !parent_devfreq->profile ||    !parent_devfreq->profile->stats ||
>>>>>>>> +        parent_devfreq->profile->stats->max_state <= 0)
>>>>>>>>            return -EINVAL;
>>>>>>>>    +    stats = devfreq->profile->stats;
>>>>>>>> +    parent_stats = parent_devfreq->profile->stats;
>>>>>>>>        /*
>>>>>>>>         * The passive governor have to get the correct frequency from OPP
>>>>>>>>         * list of parent device. Because in this case, *freq is temporary
>>>>>>>> @@ -68,21 +74,21 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>>>>         * Get the OPP table's index of decided freqeuncy by governor
>>>>>>>>         * of parent device.
>>>>>>>>         */
>>>>>>>> -    for (i = 0; i < parent_devfreq->profile->max_state; i++)
>>>>>>>> -        if (parent_devfreq->profile->freq_table[i] == *freq)
>>>>>>>> +    for (i = 0; i < parent_stats->max_state; i++)
>>>>>>>> +        if (parent_stats->freq_table[i] == *freq)
>>>>>>>>                break;
>>>>>>>>    -    if (i == parent_devfreq->profile->max_state) {
>>>>>>>> +    if (i == parent_stats->max_state) {
>>>>>>>>            ret = -EINVAL;
>>>>>>>>            goto out;
>>>>>>>>        }
>>>>>>>>          /* Get the suitable frequency by using index of parent device. */
>>>>>>>> -    if (i < devfreq->profile->max_state) {
>>>>>>>> -        child_freq = devfreq->profile->freq_table[i];
>>>>>>>> +    if (i < stats->max_state) {
>>>>>>>> +        child_freq = stats->freq_table[i];
>>>>>>>>        } else {
>>>>>>>> -        count = devfreq->profile->max_state;
>>>>>>>> -        child_freq = devfreq->profile->freq_table[count - 1];
>>>>>>>> +        count = stats->max_state;
>>>>>>>> +        child_freq = stats->freq_table[count - 1];
>>>>>>>>        }
>>>>>>>>          /* Return the suitable frequency for passive device. */
>>>>>>>> @@ -109,7 +115,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>>>>>>>>        if (ret < 0)
>>>>>>>>            goto out;
>>>>>>>>    -    if (devfreq->profile->freq_table
>>>>>>>> +    if (devfreq->profile->stats
>>>>>>>>            && (devfreq_update_status(devfreq, freq)))
>>>>>>>>            dev_err(&devfreq->dev,
>>>>>>>>                "Couldn't update frequency transition information.\n");
>>>>>>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>>>>>>> index 4ceb2a517a9c..8459af1a1583 100644
>>>>>>>> --- a/include/linux/devfreq.h
>>>>>>>> +++ b/include/linux/devfreq.h
>>>>>>>> @@ -64,6 +64,30 @@ struct devfreq_dev_status {
>>>>>>>>     */
>>>>>>>>    #define DEVFREQ_FLAG_LEAST_UPPER_BOUND        0x1
>>>>>>>>    +/**
>>>>>>>> + * struct devfreq_stats - Devfreq's transitions stats counters
>>>>>>>> + * @freq_table:        Optional list of frequencies to support statistics
>>>>>>>> + *            and freq_table must be generated in ascending order.
>>>>>>>> + * @max_state:        The size of freq_table.
>>>>>>>> + * @total_trans:    Number of devfreq transitions
>>>>>>>> + * @trans_table:    Statistics of devfreq transitions
>>>>>>>> + * @time_in_state:    Statistics of devfreq states
>>>>>>>> + * @last_time:        The last time stats were updated
>>>>>>>> + * @stats_lock:        Lock protecting trans_table, time_in_state,
>>>>>>>> + *            last_time and total_trans used for statistics
>>>>>>>> + */
>>>>>>>> +struct devfreq_stats {
>>>>>>>> +    unsigned long *freq_table;
>>>>>>>> +    unsigned int max_state;
>>>>>>>> +
>>>>>>>> +    /* information for device frequency transition */
>>>>>>>> +    unsigned int total_trans;
>>>>>>>> +    unsigned int *trans_table;
>>>>>>>> +    u64 *time_in_state;
>>>>>>>> +    unsigned long long last_time;
>>>>>>>> +    spinlock_t stats_lock;
>>>>>>>> +};
>>>>>>>> +
>>>>>>>>    /**
>>>>>>>>     * struct devfreq_dev_profile - Devfreq's user device profile
>>>>>>>>     * @initial_freq:    The operating frequency when devfreq_add_device() is
>>>>>>>> @@ -88,15 +112,7 @@ struct devfreq_dev_status {
>>>>>>>>     *            from devfreq_remove_device() call. If the user
>>>>>>>>     *            has registered devfreq->nb at a notifier-head,
>>>>>>>>     *            this is the time to unregister it.
>>>>>>>> - * @freq_table:        Optional list of frequencies to support statistics
>>>>>>>> - *            and freq_table must be generated in ascending order.
>>>>>>>> - * @max_state:        The size of freq_table.
>>>>>>>> - * @total_trans:    Number of devfreq transitions
>>>>>>>> - * @trans_table:    Statistics of devfreq transitions
>>>>>>>> - * @time_in_state:    Statistics of devfreq states
>>>>>>>> - * @last_time:        The last time stats were updated
>>>>>>>> - * @stats_lock:        Lock protecting trans_table, time_in_state,
>>>>>>>> - *            last_time and total_trans used for statistics
>>>>>>>> + * @stats:        Statistics of devfreq states and state transitions
>>>>>>>>     */
>>>>>>>>    struct devfreq_dev_profile {
>>>>>>>>        unsigned long initial_freq;
>>>>>>>> @@ -108,14 +124,7 @@ struct devfreq_dev_profile {
>>>>>>>>        int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>>>>>>>>        void (*exit)(struct device *dev);
>>>>>>>>    -    unsigned long *freq_table;
>>>>>>>> -    unsigned int max_state;
>>>>>>>> -    /* information for device frequency transition */
>>>>>>>> -    unsigned int total_trans;
>>>>>>>> -    unsigned int *trans_table;
>>>>>>>> -    u64 *time_in_state;
>>>>>>>> -    unsigned long long last_time;
>>>>>>>> -    spinlock_t stats_lock;
>>>>>>>> +    struct devfreq_stats *stats;
>>>>>>>>    };
>>>>>>>>      /**
>>>>>>>>
>>>
>>> _______________________________________________
>>> linux-arm-kernel mailing list
>>> [e-mail]
>>> https://protect2.fireeye.com/url?k=856913bb-d8f2efd8-856898f4-0cc47a31cdbc-5cb40ce5f31ed8ed&u=http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>>
>>
>>
> 
>

Bartlomiej Zolnierkiewicz Jan. 15, 2020, 3:56 p.m. UTC | #9

On 12/16/19 2:01 PM, Lukasz Luba wrote:
> Hi Bartek,
> 
> [added Dietmar, Robin, Andrzej (for upcoming DRM drm-misc-next)]
> 
> On 11/15/19 12:40 PM, Bartlomiej Zolnierkiewicz wrote:

[...]

>> Hmmm.. fixing partition_enable_opps() should be trivial but I wonder
>> why we are carrying devfreq_cooling.c code in upstream kernel at all?
> 
> Well, the devfreq_cooling.c is going to have a client in mainline:
> the GPU driver - Panfrost.
> 
> It is already in DRM branch 'drm-misc-next':
> https://patchwork.freedesktop.org/patch/342848/

OK, thanks for explaining this.

> Regarding the devfreq_cooling.c code structure.
> I am currently working on cleaning up the devfreq cooling code and
> adding Energy Model instead for private freq, power tables. It will be
> in similar fashion as it is done in cpufreq_cooling. The model will
> be also simplified so hopefully more clients would come.
> It is under internal review and will be posted shortly.

Great to hear this and thank you for working on it.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

Patch

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index d79412b0de59..d85867a91230 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -105,10 +105,11 @@  static unsigned long find_available_max_freq(struct devfreq *devfreq)
  */
 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
 {
+	struct devfreq_stats *stats = devfreq->profile->stats;
 	int lev;
 
-	for (lev = 0; lev < devfreq->profile->max_state; lev++)
-		if (freq == devfreq->profile->freq_table[lev])
+	for (lev = 0; lev < stats->max_state; lev++)
+		if (freq == stats->freq_table[lev])
 			return lev;
 
 	return -EINVAL;
@@ -117,56 +118,64 @@  static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
 static int set_freq_table(struct devfreq *devfreq)
 {
 	struct devfreq_dev_profile *profile = devfreq->profile;
+	struct devfreq_stats *stats;
 	struct dev_pm_opp *opp;
 	unsigned long freq;
-	int i, count;
+	int i, count, err = -ENOMEM;
 
 	/* Initialize the freq_table from OPP table */
 	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
 	if (count <= 0)
 		return -EINVAL;
 
-	profile->max_state = count;
-	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
-					count,
-					sizeof(*profile->freq_table),
-					GFP_KERNEL);
-	if (!profile->freq_table) {
-		profile->max_state = 0;
+	stats = devm_kzalloc(devfreq->dev.parent,
+			     sizeof(struct devfreq_stats), GFP_KERNEL);
+	if (!stats)
 		return -ENOMEM;
-	}
 
-	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
+	profile->stats = stats;
+	stats->max_state = count;
+	stats->freq_table = devm_kcalloc(devfreq->dev.parent,
+					 count,
+					 sizeof(*stats->freq_table),
+					 GFP_KERNEL);
+	if (!stats->freq_table)
+		goto err_no_mem;
+
+	for (i = 0, freq = 0; i < count; i++, freq++) {
 		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 		if (IS_ERR(opp)) {
-			devm_kfree(devfreq->dev.parent, profile->freq_table);
-			profile->max_state = 0;
-			return PTR_ERR(opp);
+			devm_kfree(devfreq->dev.parent, stats->freq_table);
+			stats->max_state = 0;
+			err = PTR_ERR(opp);
+			goto err_no_mem;
 		}
 		dev_pm_opp_put(opp);
-		profile->freq_table[i] = freq;
+		stats->freq_table[i] = freq;
 	}
 
-	profile->trans_table = devm_kzalloc(devfreq->dev.parent,
-					    array3_size(sizeof(unsigned int),
-							count, count),
-					    GFP_KERNEL);
-	if (!profile->trans_table)
+	stats->trans_table = devm_kzalloc(devfreq->dev.parent,
+					  array3_size(sizeof(unsigned int),
+						      count, count),
+					  GFP_KERNEL);
+	if (!stats->trans_table)
 		goto err_no_mem;
 
-	profile->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
-					      sizeof(*profile->time_in_state),
-					      GFP_KERNEL);
-	if (!profile->time_in_state)
+	stats->time_in_state = devm_kcalloc(devfreq->dev.parent, count,
+					    sizeof(*stats->time_in_state),
+					    GFP_KERNEL);
+	if (!stats->time_in_state)
 		goto err_no_mem;
 
-	profile->last_time = get_jiffies_64();
-	spin_lock_init(&profile->stats_lock);
+	stats->last_time = get_jiffies_64();
+	spin_lock_init(&stats->stats_lock);
 
 	return 0;
 err_no_mem:
-	profile->max_state = 0;
-	return -ENOMEM;
+	stats->max_state = 0;
+	devm_kfree(devfreq->dev.parent, profile->stats);
+	profile->stats = NULL;
+	return err;
 }
 
 /**
@@ -176,7 +185,7 @@  static int set_freq_table(struct devfreq *devfreq)
  */
 int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 {
-	struct devfreq_dev_profile *profile = devfreq->profile;
+	struct devfreq_stats *stats = devfreq->profile->stats;
 	unsigned long long cur_time;
 	int lev, prev_lev, ret = 0;
 
@@ -184,22 +193,21 @@  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 
 	/* Immediately exit if previous_freq is not initialized yet. */
 	if (!devfreq->previous_freq) {
-		spin_lock(&profile->stats_lock);
-		profile->last_time = cur_time;
-		spin_unlock(&profile->stats_lock);
+		spin_lock(&stats->stats_lock);
+		stats->last_time = cur_time;
+		spin_unlock(&stats->stats_lock);
 		return 0;
 	}
 
 	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 
-	spin_lock(&profile->stats_lock);
+	spin_lock(&stats->stats_lock);
 	if (prev_lev < 0) {
 		ret = prev_lev;
 		goto out;
 	}
 
-	profile->time_in_state[prev_lev] +=
-			 cur_time - profile->last_time;
+	stats->time_in_state[prev_lev] += cur_time - stats->last_time;
 	lev = devfreq_get_freq_level(devfreq, freq);
 	if (lev < 0) {
 		ret = lev;
@@ -207,14 +215,14 @@  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 	}
 
 	if (lev != prev_lev) {
-		profile->trans_table[(prev_lev *
-				profile->max_state) + lev]++;
-		profile->total_trans++;
+		stats->trans_table[(prev_lev *
+				stats->max_state) + lev]++;
+		stats->total_trans++;
 	}
 
 out:
-	profile->last_time = cur_time;
-	spin_unlock(&profile->stats_lock);
+	stats->last_time = cur_time;
+	spin_unlock(&stats->stats_lock);
 	return ret;
 }
 EXPORT_SYMBOL(devfreq_update_status);
@@ -504,9 +512,9 @@  void devfreq_monitor_resume(struct devfreq *devfreq)
 		queue_delayed_work(devfreq_wq, &devfreq->work,
 			msecs_to_jiffies(profile->polling_ms));
 
-	spin_lock(&profile->stats_lock);
-	profile->last_time = get_jiffies_64();
-	spin_unlock(&profile->stats_lock);
+	spin_lock(&profile->stats->stats_lock);
+	profile->stats->last_time = get_jiffies_64();
+	spin_unlock(&profile->stats->stats_lock);
 	devfreq->stop_polling = false;
 
 	if (profile->get_cur_freq &&
@@ -677,7 +685,7 @@  struct devfreq *devfreq_add_device(struct device *dev,
 	devfreq->data = data;
 	devfreq->nb.notifier_call = devfreq_notifier_call;
 
-	if (!profile->max_state && !profile->freq_table) {
+	if (!profile->stats) {
 		mutex_unlock(&devfreq->lock);
 		err = set_freq_table(devfreq);
 		if (err < 0)
@@ -1282,6 +1290,7 @@  static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 			      const char *buf, size_t count)
 {
 	struct devfreq *df = to_devfreq(dev);
+	struct devfreq_stats *stats = df->profile->stats;
 	unsigned long value;
 	int ret;
 
@@ -1297,13 +1306,13 @@  static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 			goto unlock;
 		}
 	} else {
-		unsigned long *freq_table = df->profile->freq_table;
+		unsigned long *freq_table = stats->freq_table;
 
 		/* Get minimum frequency according to sorting order */
-		if (freq_table[0] < freq_table[df->profile->max_state - 1])
+		if (freq_table[0] < freq_table[stats->max_state - 1])
 			value = freq_table[0];
 		else
-			value = freq_table[df->profile->max_state - 1];
+			value = freq_table[stats->max_state - 1];
 	}
 
 	df->min_freq = value;
@@ -1326,6 +1335,7 @@  static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 			      const char *buf, size_t count)
 {
 	struct devfreq *df = to_devfreq(dev);
+	struct devfreq_stats *stats = df->profile->stats;
 	unsigned long value;
 	int ret;
 
@@ -1341,11 +1351,11 @@  static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 			goto unlock;
 		}
 	} else {
-		unsigned long *freq_table = df->profile->freq_table;
+		unsigned long *freq_table = stats->freq_table;
 
 		/* Get maximum frequency according to sorting order */
-		if (freq_table[0] < freq_table[df->profile->max_state - 1])
-			value = freq_table[df->profile->max_state - 1];
+		if (freq_table[0] < freq_table[stats->max_state - 1])
+			value = freq_table[stats->max_state - 1];
 		else
 			value = freq_table[0];
 	}
@@ -1373,14 +1383,15 @@  static ssize_t available_frequencies_show(struct device *d,
 					  char *buf)
 {
 	struct devfreq *df = to_devfreq(d);
+	struct devfreq_stats *stats = df->profile->stats;
 	ssize_t count = 0;
 	int i;
 
 	mutex_lock(&df->lock);
 
-	for (i = 0; i < df->profile->max_state; i++)
+	for (i = 0; i < stats->max_state; i++)
 		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
-				"%lu ", df->profile->freq_table[i]);
+				"%lu ", stats->freq_table[i]);
 
 	mutex_unlock(&df->lock);
 	/* Truncate the trailing space */
@@ -1398,9 +1409,10 @@  static ssize_t trans_stat_show(struct device *dev,
 {
 	struct devfreq *devfreq = to_devfreq(dev);
 	struct devfreq_dev_profile *profile = devfreq->profile;
+	struct devfreq_stats *stats = profile->stats;
+	unsigned int max_state = stats->max_state;
 	ssize_t len;
 	int i, j;
-	unsigned int max_state = profile->max_state;
 
 	if (!devfreq->stop_polling &&
 			devfreq_update_status(devfreq, devfreq->previous_freq))
@@ -1411,45 +1423,45 @@  static ssize_t trans_stat_show(struct device *dev,
 	len = sprintf(buf, "     From  :   To\n");
 	len += sprintf(buf + len, "           :");
 
-	spin_lock(&profile->stats_lock);
+	spin_lock(&stats->stats_lock);
 	for (i = 0; i < max_state; i++)
 		len += sprintf(buf + len, "%10lu",
-				profile->freq_table[i]);
+				stats->freq_table[i]);
 
 	len += sprintf(buf + len, "   time(ms)\n");
 
 	for (i = 0; i < max_state; i++) {
-		if (profile->freq_table[i] == devfreq->previous_freq)
+		if (stats->freq_table[i] == devfreq->previous_freq)
 			len += sprintf(buf + len, "*");
 		else
 			len += sprintf(buf + len, " ");
 
 		len += sprintf(buf + len, "%10lu:",
-				profile->freq_table[i]);
+				stats->freq_table[i]);
 		for (j = 0; j < max_state; j++)
 			len += sprintf(buf + len, "%10u",
-				profile->trans_table[(i * max_state) + j]);
+				stats->trans_table[(i * max_state) + j]);
 		len += sprintf(buf + len, "%10llu\n", (u64)
-			jiffies64_to_msecs(profile->time_in_state[i]));
+			jiffies64_to_msecs(stats->time_in_state[i]));
 	}
 
 	len += sprintf(buf + len, "Total transition : %u\n",
-					profile->total_trans);
-	spin_unlock(&profile->stats_lock);
+					stats->total_trans);
+	spin_unlock(&stats->stats_lock);
 	return len;
 }
 static DEVICE_ATTR_RO(trans_stat);
 
-static void defvreq_stats_clear_table(struct devfreq_dev_profile *profile)
+static void defvreq_stats_clear_table(struct devfreq_stats *stats)
 {
-	unsigned int count = profile->max_state;
-
-	spin_lock(&profile->stats_lock);
-	memset(profile->time_in_state, 0, count * sizeof(u64));
-	memset(profile->trans_table, 0, count * count * sizeof(int));
-	profile->last_time = get_jiffies_64();
-	profile->total_trans = 0;
-	spin_unlock(&profile->stats_lock);
+	unsigned int count = stats->max_state;
+
+	spin_lock(&stats->stats_lock);
+	memset(stats->time_in_state, 0, count * sizeof(u64));
+	memset(stats->trans_table, 0, count * count * sizeof(int));
+	stats->last_time = get_jiffies_64();
+	stats->total_trans = 0;
+	spin_unlock(&stats->stats_lock);
 }
 
 static ssize_t trans_reset_store(struct device *dev,
@@ -1459,7 +1471,7 @@  static ssize_t trans_reset_store(struct device *dev,
 {
 	struct devfreq *devfreq = to_devfreq(dev);
 
-	defvreq_stats_clear_table(devfreq->profile);
+	defvreq_stats_clear_table(devfreq->profile->stats);
 
 	return count;
 }
diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
index d9f377912c10..b212aae2bb3e 100644
--- a/drivers/devfreq/exynos-bus.c
+++ b/drivers/devfreq/exynos-bus.c
@@ -496,9 +496,9 @@  static int exynos_bus_probe(struct platform_device *pdev)
 	}
 
 out:
-	max_state = bus->devfreq->profile->max_state;
-	min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
-	max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
+	max_state = profile->stats->max_state;
+	min_freq = (profile->stats->freq_table[0] / 1000);
+	max_freq = (profile->stats->freq_table[max_state - 1] / 1000);
 	pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
 			dev_name(dev), min_freq, max_freq);
 
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
index 58308948b863..b2d87a88335c 100644
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -18,6 +18,8 @@  static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
 	struct devfreq_passive_data *p_data
 			= (struct devfreq_passive_data *)devfreq->data;
 	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
+	struct devfreq_stats *parent_stats = parent_devfreq->profile->stats;
+	struct devfreq_stats *stats;
 	unsigned long child_freq = ULONG_MAX;
 	struct dev_pm_opp *opp;
 	int i, count, ret = 0;
@@ -47,10 +49,14 @@  static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
 	 * device. And then the index is used for getting the suitable
 	 * new frequency for passive devfreq device.
 	 */
-	if (!devfreq->profile || !devfreq->profile->freq_table
-		|| devfreq->profile->max_state <= 0)
+	if (!devfreq->profile || !devfreq->profile->stats ||
+	    devfreq->profile->stats->max_state <= 0 ||
+	    !parent_devfreq->profile ||	!parent_devfreq->profile->stats ||
+	    parent_devfreq->profile->stats->max_state <= 0)
 		return -EINVAL;
 
+	stats = devfreq->profile->stats;
+	parent_stats = parent_devfreq->profile->stats;
 	/*
 	 * The passive governor have to get the correct frequency from OPP
 	 * list of parent device. Because in this case, *freq is temporary
@@ -68,21 +74,21 @@  static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
 	 * Get the OPP table's index of decided freqeuncy by governor
 	 * of parent device.
 	 */
-	for (i = 0; i < parent_devfreq->profile->max_state; i++)
-		if (parent_devfreq->profile->freq_table[i] == *freq)
+	for (i = 0; i < parent_stats->max_state; i++)
+		if (parent_stats->freq_table[i] == *freq)
 			break;
 
-	if (i == parent_devfreq->profile->max_state) {
+	if (i == parent_stats->max_state) {
 		ret = -EINVAL;
 		goto out;
 	}
 
 	/* Get the suitable frequency by using index of parent device. */
-	if (i < devfreq->profile->max_state) {
-		child_freq = devfreq->profile->freq_table[i];
+	if (i < stats->max_state) {
+		child_freq = stats->freq_table[i];
 	} else {
-		count = devfreq->profile->max_state;
-		child_freq = devfreq->profile->freq_table[count - 1];
+		count = stats->max_state;
+		child_freq = stats->freq_table[count - 1];
 	}
 
 	/* Return the suitable frequency for passive device. */
@@ -109,7 +115,7 @@  static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
 	if (ret < 0)
 		goto out;
 
-	if (devfreq->profile->freq_table
+	if (devfreq->profile->stats
 		&& (devfreq_update_status(devfreq, freq)))
 		dev_err(&devfreq->dev,
 			"Couldn't update frequency transition information.\n");
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 4ceb2a517a9c..8459af1a1583 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -64,6 +64,30 @@  struct devfreq_dev_status {
  */
 #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1
 
+/**
+ * struct devfreq_stats - Devfreq's transitions stats counters
+ * @freq_table:		Optional list of frequencies to support statistics
+ *			and freq_table must be generated in ascending order.
+ * @max_state:		The size of freq_table.
+ * @total_trans:	Number of devfreq transitions
+ * @trans_table:	Statistics of devfreq transitions
+ * @time_in_state:	Statistics of devfreq states
+ * @last_time:		The last time stats were updated
+ * @stats_lock:		Lock protecting trans_table, time_in_state,
+ *			last_time and total_trans used for statistics
+ */
+struct devfreq_stats {
+	unsigned long *freq_table;
+	unsigned int max_state;
+
+	/* information for device frequency transition */
+	unsigned int total_trans;
+	unsigned int *trans_table;
+	u64 *time_in_state;
+	unsigned long long last_time;
+	spinlock_t stats_lock;
+};
+
 /**
  * struct devfreq_dev_profile - Devfreq's user device profile
  * @initial_freq:	The operating frequency when devfreq_add_device() is
@@ -88,15 +112,7 @@  struct devfreq_dev_status {
  *			from devfreq_remove_device() call. If the user
  *			has registered devfreq->nb at a notifier-head,
  *			this is the time to unregister it.
- * @freq_table:		Optional list of frequencies to support statistics
- *			and freq_table must be generated in ascending order.
- * @max_state:		The size of freq_table.
- * @total_trans:	Number of devfreq transitions
- * @trans_table:	Statistics of devfreq transitions
- * @time_in_state:	Statistics of devfreq states
- * @last_time:		The last time stats were updated
- * @stats_lock:		Lock protecting trans_table, time_in_state,
- *			last_time and total_trans used for statistics
+ * @stats:		Statistics of devfreq states and state transitions
  */
 struct devfreq_dev_profile {
 	unsigned long initial_freq;
@@ -108,14 +124,7 @@  struct devfreq_dev_profile {
 	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
 	void (*exit)(struct device *dev);
 
-	unsigned long *freq_table;
-	unsigned int max_state;
-	/* information for device frequency transition */
-	unsigned int total_trans;
-	unsigned int *trans_table;
-	u64 *time_in_state;
-	unsigned long long last_time;
-	spinlock_t stats_lock;
+	struct devfreq_stats *stats;
 };
 
 /**