diff mbox series

[v1,4/5] PM / devfreq: tegra30: Use clk_round_rate_unboundly()

Message ID 20200330231617.17079-5-digetx@gmail.com
State Changes Requested, archived
Delegated to: Chanwoo Choi
Headers show
Series NVIDIA Tegra devfreq drivers improvements | expand

Commit Message

Dmitry Osipenko March 30, 2020, 11:16 p.m. UTC
The clk_round_rate() doesn't work for us properly if clock rate is bounded
by a min/max rate that is requested by some other clk-user because we're
building devfreq's OPP table based on the rounding.

In particular this becomes a problem if display driver is probed earlier
than devfreq, and thus, display adds a memory bandwidth request using
interconnect API, which results in a minimum clock-rate being set for
the memory clk. In a result, the lowest devfreq OPP rate is getting
limited to the minimum rate imposed by the display driver.

Let's use new clk_round_rate_unboundly() that resolves the problem by
rounding clock rate without taking into account min/max limits imposed by
active clk users.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/devfreq/tegra30-devfreq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Chanwoo Choi March 31, 2020, 11:22 p.m. UTC | #1
On 3/31/20 8:16 AM, Dmitry Osipenko wrote:
> The clk_round_rate() doesn't work for us properly if clock rate is bounded
> by a min/max rate that is requested by some other clk-user because we're
> building devfreq's OPP table based on the rounding.
> 
> In particular this becomes a problem if display driver is probed earlier
> than devfreq, and thus, display adds a memory bandwidth request using
> interconnect API, which results in a minimum clock-rate being set for
> the memory clk. In a result, the lowest devfreq OPP rate is getting
> limited to the minimum rate imposed by the display driver.
> 
> Let's use new clk_round_rate_unboundly() that resolves the problem by
> rounding clock rate without taking into account min/max limits imposed by
> active clk users.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/devfreq/tegra30-devfreq.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 28b2c7ca416e..34f6291e880c 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -834,7 +834,7 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  
>  	reset_control_deassert(tegra->reset);
>  
> -	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
> +	rate = clk_round_rate_unboundly(tegra->emc_clock, ULONG_MAX);
>  	if (rate < 0) {
>  		dev_err(&pdev->dev, "Failed to round clock rate: %ld\n", rate);
>  		return rate;
> @@ -849,7 +849,7 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  	}
>  
>  	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
> -		rate = clk_round_rate(tegra->emc_clock, rate);
> +		rate = clk_round_rate_unboundly(tegra->emc_clock, rate);
>  
>  		if (rate < 0) {
>  			dev_err(&pdev->dev,
> 

Firstly, patch2 have to be reviewed for this patch.
I have no any objection. It looks good to me.

If patch1 get the confirmation from clock maintainer,
feel free to add my acked tag:
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Chanwoo Choi March 31, 2020, 11:23 p.m. UTC | #2
On 4/1/20 8:22 AM, Chanwoo Choi wrote:
> On 3/31/20 8:16 AM, Dmitry Osipenko wrote:
>> The clk_round_rate() doesn't work for us properly if clock rate is bounded
>> by a min/max rate that is requested by some other clk-user because we're
>> building devfreq's OPP table based on the rounding.
>>
>> In particular this becomes a problem if display driver is probed earlier
>> than devfreq, and thus, display adds a memory bandwidth request using
>> interconnect API, which results in a minimum clock-rate being set for
>> the memory clk. In a result, the lowest devfreq OPP rate is getting
>> limited to the minimum rate imposed by the display driver.
>>
>> Let's use new clk_round_rate_unboundly() that resolves the problem by
>> rounding clock rate without taking into account min/max limits imposed by
>> active clk users.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/devfreq/tegra30-devfreq.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
>> index 28b2c7ca416e..34f6291e880c 100644
>> --- a/drivers/devfreq/tegra30-devfreq.c
>> +++ b/drivers/devfreq/tegra30-devfreq.c
>> @@ -834,7 +834,7 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  
>>  	reset_control_deassert(tegra->reset);
>>  
>> -	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
>> +	rate = clk_round_rate_unboundly(tegra->emc_clock, ULONG_MAX);
>>  	if (rate < 0) {
>>  		dev_err(&pdev->dev, "Failed to round clock rate: %ld\n", rate);
>>  		return rate;
>> @@ -849,7 +849,7 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  	}
>>  
>>  	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
>> -		rate = clk_round_rate(tegra->emc_clock, rate);
>> +		rate = clk_round_rate_unboundly(tegra->emc_clock, rate);
>>  
>>  		if (rate < 0) {
>>  			dev_err(&pdev->dev,
>>
> 
> Firstly, patch2 have to be reviewed for this patch.
> I have no any objection. It looks good to me.
> 
> If patch1 get the confirmation from clock maintainer,

Sorry. I mean the patch2 about clk_round_rate_unboundly() function.
instead of patch1.

> feel free to add my acked tag:
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
> 
>
diff mbox series

Patch

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index 28b2c7ca416e..34f6291e880c 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -834,7 +834,7 @@  static int tegra_devfreq_probe(struct platform_device *pdev)
 
 	reset_control_deassert(tegra->reset);
 
-	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
+	rate = clk_round_rate_unboundly(tegra->emc_clock, ULONG_MAX);
 	if (rate < 0) {
 		dev_err(&pdev->dev, "Failed to round clock rate: %ld\n", rate);
 		return rate;
@@ -849,7 +849,7 @@  static int tegra_devfreq_probe(struct platform_device *pdev)
 	}
 
 	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
-		rate = clk_round_rate(tegra->emc_clock, rate);
+		rate = clk_round_rate_unboundly(tegra->emc_clock, rate);
 
 		if (rate < 0) {
 			dev_err(&pdev->dev,