[PATCH] cpufreq: tegra: update comment for clarity

[PATCH] cpufreq: tegra: update comment for clarity

[Viresh Kumar]

Tegra's driver got updated a bit (00917dd cpufreq: Tegra: implement intermediate
frequency callbacks) and implements new 'intermediate freq' infrastructure of
core. Above commit updated comments about when to call
clk_prepare_enable(pll_x_clk) and Doug wasn't satisfied with those comments and
said this:

> The "Though when target-freq is intermediate freq, we don't need to
> take this reference." makes me think that this function is actually
> called when target-freq is intermediate freq.  I don't think it is,
> right?

For better clarity just make that comment more explicit about when we call
tegra_target_intermediate(). Wasn't sure if we actually need a commit for this,
but anyway lets other decide if its worth enough :)

Reported-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/tegra-cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c
index a5fbc0a..48bc89b 100644
--- a/drivers/cpufreq/tegra-cpufreq.c
+++ b/drivers/cpufreq/tegra-cpufreq.c
@@ -73,7 +73,7 @@ static int tegra_target_intermediate(struct cpufreq_policy *policy,
 	 * off when we move the cpu off of it as enabling it again while we
 	 * switch to it from tegra_target() would take additional time. Though
 	 * when target-freq is intermediate freq, we don't need to take this
-	 * reference.
+	 * reference and so this routine isn't called at all.
 	 */
 	clk_prepare_enable(pll_x_clk);
 
-- 
2.0.0.rc2

Re: [PATCH] cpufreq: tegra: update comment for clarity

[Doug Anderson]

Viresh,

On Thu, Jun 5, 2014 at 9:38 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> Tegra's driver got updated a bit (00917dd cpufreq: Tegra: implement intermediate
> frequency callbacks) and implements new 'intermediate freq' infrastructure of
> core. Above commit updated comments about when to call
> clk_prepare_enable(pll_x_clk) and Doug wasn't satisfied with those comments and
> said this:
>
>> The "Though when target-freq is intermediate freq, we don't need to
>> take this reference." makes me think that this function is actually
>> called when target-freq is intermediate freq.  I don't think it is,
>> right?
>
> For better clarity just make that comment more explicit about when we call
> tegra_target_intermediate(). Wasn't sure if we actually need a commit for this,
> but anyway lets other decide if its worth enough :)
>
> Reported-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  drivers/cpufreq/tegra-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c
> index a5fbc0a..48bc89b 100644
> --- a/drivers/cpufreq/tegra-cpufreq.c
> +++ b/drivers/cpufreq/tegra-cpufreq.c
> @@ -73,7 +73,7 @@ static int tegra_target_intermediate(struct cpufreq_policy *policy,
>          * off when we move the cpu off of it as enabling it again while we
>          * switch to it from tegra_target() would take additional time. Though
>          * when target-freq is intermediate freq, we don't need to take this
> -        * reference.
> +        * reference and so this routine isn't called at all.

I'm OK either way, so up to others.

Reviewed-by: Doug Anderson <dianders@chromium.org>

Re: [PATCH] cpufreq: tegra: update comment for clarity

[Stephen Warren]

On 06/05/2014 10:38 PM, Viresh Kumar wrote:
> Tegra's driver got updated a bit (00917dd cpufreq: Tegra: implement intermediate
> frequency callbacks) and implements new 'intermediate freq' infrastructure of
> core. Above commit updated comments about when to call
> clk_prepare_enable(pll_x_clk) and Doug wasn't satisfied with those comments and
> said this:
> 
>> The "Though when target-freq is intermediate freq, we don't need to
>> take this reference." makes me think that this function is actually
>> called when target-freq is intermediate freq.  I don't think it is,
>> right?
> 
> For better clarity just make that comment more explicit about when we call
> tegra_target_intermediate(). Wasn't sure if we actually need a commit for this,
> but anyway lets other decide if its worth enough :)

> diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c
> index a5fbc0a..48bc89b 100644
> --- a/drivers/cpufreq/tegra-cpufreq.c
> +++ b/drivers/cpufreq/tegra-cpufreq.c
> @@ -73,7 +73,7 @@ static int tegra_target_intermediate(struct cpufreq_policy *policy,
>  	 * off when we move the cpu off of it as enabling it again while we
>  	 * switch to it from tegra_target() would take additional time. Though
>  	 * when target-freq is intermediate freq, we don't need to take this
> -	 * reference.
> +	 * reference and so this routine isn't called at all.
>  	 */
>  	clk_prepare_enable(pll_x_clk);

I would remove the word "so" in the added line; the function is not
called because we don't need to use an intermediate frequency, not
because we don't need to take a reference to pll_x. With that change,

Reviewed-by: Stephen Warren <swarren@nvidia.com>

[PATCH Resend] cpufreq: tegra: update comment for clarity

[Viresh Kumar]

Tegra's driver got updated a bit (00917dd cpufreq: Tegra: implement intermediate
frequency callbacks) and implements new 'intermediate freq' infrastructure of
core. Above commit updated comments about when to call
clk_prepare_enable(pll_x_clk) and Doug wasn't satisfied with those comments and
said this:

> The "Though when target-freq is intermediate freq, we don't need to
> take this reference." makes me think that this function is actually
> called when target-freq is intermediate freq.  I don't think it is,
> right?

For better clarity just make that comment more explicit about when we call
tegra_target_intermediate().

Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reported-and-reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
Resend: Improved comment as suggested by Stephen.

 drivers/cpufreq/tegra-cpufreq.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c
index a5fbc0a..8084c7f 100644
--- a/drivers/cpufreq/tegra-cpufreq.c
+++ b/drivers/cpufreq/tegra-cpufreq.c
@@ -71,9 +71,12 @@ static int tegra_target_intermediate(struct cpufreq_policy *policy,
 	/*
 	 * Take an extra reference to the main pll so it doesn't turn
 	 * off when we move the cpu off of it as enabling it again while we
-	 * switch to it from tegra_target() would take additional time. Though
-	 * when target-freq is intermediate freq, we don't need to take this
-	 * reference.
+	 * switch to it from tegra_target() would take additional time.
+	 *
+	 * When target-freq is equal to intermediate freq we don't need to
+	 * switch to an intermediate freq and so this routine isn't called.
+	 * Also, we wouldn't be using pll_x anymore and must not take extra
+	 * reference to it, as it can be disabled now to save some power.
 	 */
 	clk_prepare_enable(pll_x_clk);
 
-- 
2.0.0.rc2

Re: [PATCH Resend] cpufreq: tegra: update comment for clarity

[Rafael J. Wysocki]

On Tuesday, June 10, 2014 10:27:12 AM Viresh Kumar wrote:
> Tegra's driver got updated a bit (00917dd cpufreq: Tegra: implement intermediate
> frequency callbacks) and implements new 'intermediate freq' infrastructure of
> core. Above commit updated comments about when to call
> clk_prepare_enable(pll_x_clk) and Doug wasn't satisfied with those comments and
> said this:
> 
> > The "Though when target-freq is intermediate freq, we don't need to
> > take this reference." makes me think that this function is actually
> > called when target-freq is intermediate freq.  I don't think it is,
> > right?
> 
> For better clarity just make that comment more explicit about when we call
> tegra_target_intermediate().
> 
> Reviewed-by: Stephen Warren <swarren@nvidia.com>
> Reported-and-reviewed-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> Resend: Improved comment as suggested by Stephen.

Applied to bleeding-edge, thanks!

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.