Re: leds-pwm: issue in __led_pwm_set()

[Milo Kim <milo.kim@ti.com>]

On 09/28/2013 04:46 AM, Alexandre Belloni wrote:
> On 27/09/2013 20:34, Alexandre Belloni wrote:
>>
>> Ok, I tested that and it seems to be working fine.
>>
>
> One last question though. What about power management ?
>
> For example, in pwm_bl, pwm_backlight_suspend calls:
>
>      pwm_config(pb->pwm, 0, pb->period);
>      pwm_disable(pb->pwm);
>
> Which is fine because it will correctly set up the PWM to a low level.

OK.

> Then, to disable the pwm itself and its clock, I suppose we would have
> to define some pm_ops in atmel_pwm, am I right ?

Maybe the suspend/resume() can be handled by the PWM driver.
However, not every PWM consumer of atmel-pwm needs the PM code.
I think it would be better if those are handled by each the PWM consumer.

> So we will have to be extra careful to correctly set a low level on the
> pin at that time.

If you only care about the leds-pwm, then no additional handling is 
required.
The LED subsystem provides a 'LED_CORE_SUSPENDRESUME' flag which enables 
the PM automatically.
The brightness is set to 0 forcedly on the suspend, and the stored 
brightness is recovered on the resume.
The leds-pwm driver enables this flag.
On the suspend mode, pwm_config() and pwm_disable() are called in 
__led_pwm_set(). That's exactly what you need.

Best regards,
Milo