diff mbox series

[v3] cpufreq: tegra194: get consistent cpuinfo_cur_freq

Message ID 1602668171-30104-1-git-send-email-sumitg@nvidia.com (mailing list archive)
State New, archived
Headers show
Series [v3] cpufreq: tegra194: get consistent cpuinfo_cur_freq | expand

Commit Message

Sumit Gupta Oct. 14, 2020, 9:36 a.m. UTC
Frequency returned by 'cpuinfo_cur_freq' using counters is not fixed
and keeps changing slightly. This change returns a consistent value
from freq_table. If the reconstructed frequency has acceptable delta
from the last written value, then return the frequency corresponding
to the last written ndiv value from freq_table. Otherwise, print a
warning and return the reconstructed freq.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---

Sending only this patch as other patch not required after the change
to convert 'pr_warn' to 'pr_info' in cpufreq core for unlisted freq.
Changelog
v1[2] -> v3:
- Removed unwanted checks for cpu_online and max cluster number
- Used WARN_ON_ONCE to avoid print flooding.

v1[1] -> v2:
- Minor changes to improve comments and reduce debug prints.
- Get freq table from cluster specific data instead of policy.

[2] https://marc.info/?l=linux-tegra&m=160216218511280&w=2
[1] https://marc.info/?l=linux-arm-kernel&m=160028821117535&w=2

 drivers/cpufreq/tegra194-cpufreq.c | 62 ++++++++++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 9 deletions(-)

Comments

Sumit Gupta Oct. 27, 2020, 6:16 a.m. UTC | #1
Ping.

> 
> Frequency returned by 'cpuinfo_cur_freq' using counters is not fixed
> and keeps changing slightly. This change returns a consistent value
> from freq_table. If the reconstructed frequency has acceptable delta
> from the last written value, then return the frequency corresponding
> to the last written ndiv value from freq_table. Otherwise, print a
> warning and return the reconstructed freq.
> 
> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> ---
> 
> Sending only this patch as other patch not required after the change
> to convert 'pr_warn' to 'pr_info' in cpufreq core for unlisted freq.
> Changelog
> v1[2] -> v3:
> - Removed unwanted checks for cpu_online and max cluster number
> - Used WARN_ON_ONCE to avoid print flooding.
> 
> v1[1] -> v2:
> - Minor changes to improve comments and reduce debug prints.
> - Get freq table from cluster specific data instead of policy.
> 
> [2] https://marc.info/?l=linux-tegra&m=160216218511280&w=2
> [1] https://marc.info/?l=linux-arm-kernel&m=160028821117535&w=2
> 
>   drivers/cpufreq/tegra194-cpufreq.c | 62 ++++++++++++++++++++++++++++++++------
>   1 file changed, 53 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
> index e1d931c..7901587 100644
> --- a/drivers/cpufreq/tegra194-cpufreq.c
> +++ b/drivers/cpufreq/tegra194-cpufreq.c
> @@ -180,9 +180,61 @@ static unsigned int tegra194_get_speed_common(u32 cpu, u32 delay)
>          return (rate_mhz * KHZ); /* in KHz */
>   }
> 
> +static void get_cpu_ndiv(void *ndiv)
> +{
> +       u64 ndiv_val;
> +
> +       asm volatile("mrs %0, s3_0_c15_c0_4" : "=r" (ndiv_val) : );
> +
> +       *(u64 *)ndiv = ndiv_val;
> +}
> +
> +static void set_cpu_ndiv(void *data)
> +{
> +       struct cpufreq_frequency_table *tbl = data;
> +       u64 ndiv_val = (u64)tbl->driver_data;
> +
> +       asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
> +}
> +
>   static unsigned int tegra194_get_speed(u32 cpu)
>   {
> -       return tegra194_get_speed_common(cpu, US_DELAY);
> +       struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
> +       struct cpufreq_frequency_table *pos;
> +       unsigned int rate;
> +       u64 ndiv;
> +       int ret;
> +       u32 cl;
> +
> +       smp_call_function_single(cpu, get_cpu_cluster, &cl, true);
> +
> +       /* reconstruct actual cpu freq using counters */
> +       rate = tegra194_get_speed_common(cpu, US_DELAY);
> +
> +       /* get last written ndiv value */
> +       ret = smp_call_function_single(cpu, get_cpu_ndiv, &ndiv, true);
> +       if (WARN_ON_ONCE(ret))
> +               return rate;
> +
> +       /*
> +        * If the reconstructed frequency has acceptable delta from
> +        * the last written value, then return freq corresponding
> +        * to the last written ndiv value from freq_table. This is
> +        * done to return consistent value.
> +        */
> +       cpufreq_for_each_valid_entry(pos, data->tables[cl]) {
> +               if (pos->driver_data != ndiv)
> +                       continue;
> +
> +               if (abs(pos->frequency - rate) > 115200) {
> +                       pr_warn("cpufreq: cpu%d,cur:%u,set:%u,set ndiv:%llu\n",
> +                               cpu, rate, pos->frequency, ndiv);
> +               } else {
> +                       rate = pos->frequency;
> +               }
> +               break;
> +       }
> +       return rate;
>   }
> 
>   static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
> @@ -209,14 +261,6 @@ static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
>          return 0;
>   }
> 
> -static void set_cpu_ndiv(void *data)
> -{
> -       struct cpufreq_frequency_table *tbl = data;
> -       u64 ndiv_val = (u64)tbl->driver_data;
> -
> -       asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
> -}
> -
>   static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
>                                         unsigned int index)
>   {
> --
> 2.7.4
>
Viresh Kumar Oct. 27, 2020, 6:58 a.m. UTC | #2
On 27-10-20, 11:46, Sumit Gupta wrote:
> Ping.

I was waiting for 5.10-rc1 to be released before I can start applying stuff for
5.11. Now that it is released, I will apply this.
Sumit Gupta Oct. 27, 2020, 7:05 a.m. UTC | #3
Thank you.

On 27/10/20 12:28 PM, Viresh Kumar wrote:
> External email: Use caution opening links or attachments
> 
> 
> On 27-10-20, 11:46, Sumit Gupta wrote:
>> Ping.
> 
> I was waiting for 5.10-rc1 to be released before I can start applying stuff for
> 5.11. Now that it is released, I will apply this.
> 
> --
> viresh
>
Viresh Kumar Oct. 28, 2020, 6:10 a.m. UTC | #4
On 14-10-20, 15:06, Sumit Gupta wrote:
> Frequency returned by 'cpuinfo_cur_freq' using counters is not fixed
> and keeps changing slightly. This change returns a consistent value
> from freq_table. If the reconstructed frequency has acceptable delta
> from the last written value, then return the frequency corresponding
> to the last written ndiv value from freq_table. Otherwise, print a
> warning and return the reconstructed freq.
> 
> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> ---
> 
> Sending only this patch as other patch not required after the change
> to convert 'pr_warn' to 'pr_info' in cpufreq core for unlisted freq.
> Changelog
> v1[2] -> v3:
> - Removed unwanted checks for cpu_online and max cluster number
> - Used WARN_ON_ONCE to avoid print flooding.
> 
> v1[1] -> v2:
> - Minor changes to improve comments and reduce debug prints.
> - Get freq table from cluster specific data instead of policy.
> 
> [2] https://marc.info/?l=linux-tegra&m=160216218511280&w=2
> [1] https://marc.info/?l=linux-arm-kernel&m=160028821117535&w=2
> 
>  drivers/cpufreq/tegra194-cpufreq.c | 62 ++++++++++++++++++++++++++++++++------
>  1 file changed, 53 insertions(+), 9 deletions(-)

Applied. Thanks.
diff mbox series

Patch

diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
index e1d931c..7901587 100644
--- a/drivers/cpufreq/tegra194-cpufreq.c
+++ b/drivers/cpufreq/tegra194-cpufreq.c
@@ -180,9 +180,61 @@  static unsigned int tegra194_get_speed_common(u32 cpu, u32 delay)
 	return (rate_mhz * KHZ); /* in KHz */
 }
 
+static void get_cpu_ndiv(void *ndiv)
+{
+	u64 ndiv_val;
+
+	asm volatile("mrs %0, s3_0_c15_c0_4" : "=r" (ndiv_val) : );
+
+	*(u64 *)ndiv = ndiv_val;
+}
+
+static void set_cpu_ndiv(void *data)
+{
+	struct cpufreq_frequency_table *tbl = data;
+	u64 ndiv_val = (u64)tbl->driver_data;
+
+	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
+}
+
 static unsigned int tegra194_get_speed(u32 cpu)
 {
-	return tegra194_get_speed_common(cpu, US_DELAY);
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	struct cpufreq_frequency_table *pos;
+	unsigned int rate;
+	u64 ndiv;
+	int ret;
+	u32 cl;
+
+	smp_call_function_single(cpu, get_cpu_cluster, &cl, true);
+
+	/* reconstruct actual cpu freq using counters */
+	rate = tegra194_get_speed_common(cpu, US_DELAY);
+
+	/* get last written ndiv value */
+	ret = smp_call_function_single(cpu, get_cpu_ndiv, &ndiv, true);
+	if (WARN_ON_ONCE(ret))
+		return rate;
+
+	/*
+	 * If the reconstructed frequency has acceptable delta from
+	 * the last written value, then return freq corresponding
+	 * to the last written ndiv value from freq_table. This is
+	 * done to return consistent value.
+	 */
+	cpufreq_for_each_valid_entry(pos, data->tables[cl]) {
+		if (pos->driver_data != ndiv)
+			continue;
+
+		if (abs(pos->frequency - rate) > 115200) {
+			pr_warn("cpufreq: cpu%d,cur:%u,set:%u,set ndiv:%llu\n",
+				cpu, rate, pos->frequency, ndiv);
+		} else {
+			rate = pos->frequency;
+		}
+		break;
+	}
+	return rate;
 }
 
 static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
@@ -209,14 +261,6 @@  static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
 	return 0;
 }
 
-static void set_cpu_ndiv(void *data)
-{
-	struct cpufreq_frequency_table *tbl = data;
-	u64 ndiv_val = (u64)tbl->driver_data;
-
-	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
-}
-
 static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
 				       unsigned int index)
 {