Re: [PATCH 2/2] pwm: rcar: add suspend/resume support

[Geert Uytterhoeven]

Hi Shimoda-san,

On Tue, Mar 13, 2018 at 8:04 AM, Yoshihiro Shimoda
 wrote:
>> From: Geert Uytterhoeven, Sent: Friday, March 9, 2018 9:53 PM
>> On Fri, Mar 9, 2018 at 12:54 PM, Yoshihiro Shimoda
>>  wrote:
>> > This patch adds suspend/resume support for Renesas PWM driver.
>> >
>> > Signed-off-by: Yoshihiro Shimoda 
>>
>> Thanks for your patch!
>
> Thank you for your review!
>
>> > --- a/drivers/pwm/pwm-rcar.c
>> > +++ b/drivers/pwm/pwm-rcar.c
>> > @@ -254,11 +254,38 @@ static int rcar_pwm_remove(struct platform_device 
>> > *pdev)
>> >  };
>> >  MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);
>> >
>> > +#ifdef CONFIG_PM_SLEEP
>> > +static int rcar_pwm_suspend(struct device *dev)
>> > +{
>> > +   pm_runtime_put(dev);
>> > +
>> > +   return 0;
>> > +}
>> > +
>> > +static int rcar_pwm_resume(struct device *dev)
>> > +{
>> > +   struct platform_device *pdev = to_platform_device(dev);
>> > +   struct rcar_pwm_chip *rcar_pwm = platform_get_drvdata(pdev);
>> > +   struct pwm_chip *chip = _pwm->chip;
>> > +   struct pwm_device *pwm = >pwms[0];
>> > +
>> > +   pm_runtime_get_sync(dev);
>>
>> This enables the module clock unconditionally, so you can restore the
>> register values below...
>>
>> > +   rcar_pwm_config(chip, pwm, pwm->state.duty_cycle, 
>> > pwm->state.period);
>> > +   if (pwm_is_enabled(pwm))
>> > +   rcar_pwm_enable(chip, pwm);
>>
>> ... but shouldn't you disable the clock again if the PWM is not in use,
>> like below?
>>
>> else
>> pm_runtime_put(dev);
>
> Thank you for the pointing out.
> I realize that this suspend/resume function should check PWMF_REQUESTED 
> condition
> because this driver enables the clock after the .request(rcar_pwm_request) 
> was called.
> So, I will fix this patch in v2.

OK.

> Also, reducing power point of view, this driver should call not 
> pm_runtime_get_sync/put()
> in _request/_free(). But, I would like to implement such code as a next step 
> :)

That makes sense.  I was already wondering whether those are the best
locations to call the pm_runtime_*() functions, but I'm not sufficiently
familiar with the PWM subsystem.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

RE: [PATCH 2/2] pwm: rcar: add suspend/resume support

[Yoshihiro Shimoda]

Hi Geert-san,

> From: Geert Uytterhoeven, Sent: Friday, March 9, 2018 9:53 PM
> 
> Hi Shimoda-san,
> 
> On Fri, Mar 9, 2018 at 12:54 PM, Yoshihiro Shimoda
>  wrote:
> > This patch adds suspend/resume support for Renesas PWM driver.
> >
> > Signed-off-by: Yoshihiro Shimoda 
> 
> Thanks for your patch!

Thank you for your review!

> > --- a/drivers/pwm/pwm-rcar.c
> > +++ b/drivers/pwm/pwm-rcar.c
> > @@ -254,11 +254,38 @@ static int rcar_pwm_remove(struct platform_device 
> > *pdev)
> >  };
> >  MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);
> >
> > +#ifdef CONFIG_PM_SLEEP
> > +static int rcar_pwm_suspend(struct device *dev)
> > +{
> > +   pm_runtime_put(dev);
> > +
> > +   return 0;
> > +}
> > +
> > +static int rcar_pwm_resume(struct device *dev)
> > +{
> > +   struct platform_device *pdev = to_platform_device(dev);
> > +   struct rcar_pwm_chip *rcar_pwm = platform_get_drvdata(pdev);
> > +   struct pwm_chip *chip = _pwm->chip;
> > +   struct pwm_device *pwm = >pwms[0];
> > +
> > +   pm_runtime_get_sync(dev);
> 
> This enables the module clock unconditionally, so you can restore the
> register values below...
> 
> > +   rcar_pwm_config(chip, pwm, pwm->state.duty_cycle, 
> > pwm->state.period);
> > +   if (pwm_is_enabled(pwm))
> > +   rcar_pwm_enable(chip, pwm);
> 
> ... but shouldn't you disable the clock again if the PWM is not in use,
> like below?
> 
> else
> pm_runtime_put(dev);

Thank you for the pointing out.
I realize that this suspend/resume function should check PWMF_REQUESTED 
condition
because this driver enables the clock after the .request(rcar_pwm_request) was 
called.
So, I will fix this patch in v2.

Also, reducing power point of view, this driver should call not 
pm_runtime_get_sync/put()
in _request/_free(). But, I would like to implement such code as a next step :)

Best regards,
Yoshihiro Shimoda

> Likewise, I think the call to "pm_runtime_put(dev)" in rcar_pwm_suspend()
> should be protected by a pwm_is_enabled(pwm) check.
> 
> > +   return 0;
> > +}
> 
> Gr{oetje,eeting}s,
> 
> Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- 
> ge...@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like 
> that.
> -- Linus Torvalds

Re: [PATCH 2/2] pwm: rcar: add suspend/resume support

[Geert Uytterhoeven]

Hi Shimoda-san,

On Fri, Mar 9, 2018 at 12:54 PM, Yoshihiro Shimoda
 wrote:
> This patch adds suspend/resume support for Renesas PWM driver.
>
> Signed-off-by: Yoshihiro Shimoda 

Thanks for your patch!

> --- a/drivers/pwm/pwm-rcar.c
> +++ b/drivers/pwm/pwm-rcar.c
> @@ -254,11 +254,38 @@ static int rcar_pwm_remove(struct platform_device *pdev)
>  };
>  MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);
>
> +#ifdef CONFIG_PM_SLEEP
> +static int rcar_pwm_suspend(struct device *dev)
> +{
> +   pm_runtime_put(dev);
> +
> +   return 0;
> +}
> +
> +static int rcar_pwm_resume(struct device *dev)
> +{
> +   struct platform_device *pdev = to_platform_device(dev);
> +   struct rcar_pwm_chip *rcar_pwm = platform_get_drvdata(pdev);
> +   struct pwm_chip *chip = _pwm->chip;
> +   struct pwm_device *pwm = >pwms[0];
> +
> +   pm_runtime_get_sync(dev);

This enables the module clock unconditionally, so you can restore the
register values below...

> +   rcar_pwm_config(chip, pwm, pwm->state.duty_cycle, pwm->state.period);
> +   if (pwm_is_enabled(pwm))
> +   rcar_pwm_enable(chip, pwm);

... but shouldn't you disable the clock again if the PWM is not in use,
like below?

else
pm_runtime_put(dev);

Likewise, I think the call to "pm_runtime_put(dev)" in rcar_pwm_suspend()
should be protected by a pwm_is_enabled(pwm) check.

> +   return 0;
> +}

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

[PATCH 2/2] pwm: rcar: add suspend/resume support

[Yoshihiro Shimoda]

This patch adds suspend/resume support for Renesas PWM driver.

Signed-off-by: Yoshihiro Shimoda 
---
 drivers/pwm/pwm-rcar.c | 27 +++
 1 file changed, 27 insertions(+)

diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index b942010..f62045c 100644
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -254,11 +254,38 @@ static int rcar_pwm_remove(struct platform_device *pdev)
 };
 MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);
 
+#ifdef CONFIG_PM_SLEEP
+static int rcar_pwm_suspend(struct device *dev)
+{
+   pm_runtime_put(dev);
+
+   return 0;
+}
+
+static int rcar_pwm_resume(struct device *dev)
+{
+   struct platform_device *pdev = to_platform_device(dev);
+   struct rcar_pwm_chip *rcar_pwm = platform_get_drvdata(pdev);
+   struct pwm_chip *chip = _pwm->chip;
+   struct pwm_device *pwm = >pwms[0];
+
+   pm_runtime_get_sync(dev);
+
+   rcar_pwm_config(chip, pwm, pwm->state.duty_cycle, pwm->state.period);
+   if (pwm_is_enabled(pwm))
+   rcar_pwm_enable(chip, pwm);
+
+   return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+static SIMPLE_DEV_PM_OPS(rcar_pwm_pm_ops, rcar_pwm_suspend, rcar_pwm_resume);
+
 static struct platform_driver rcar_pwm_driver = {
.probe = rcar_pwm_probe,
.remove = rcar_pwm_remove,
.driver = {
.name = "pwm-rcar",
+   .pm = _pwm_pm_ops,
.of_match_table = of_match_ptr(rcar_pwm_of_table),
}
 };
-- 
1.9.1