Re: [PATCH v4 2/4] drm/rockchip: add an common abstracted PSR driver

[Yakir Yang <ykk@rock-chips.com>]

Doug,

On 07/23/2016 12:04 PM, Doug Anderson wrote:
> Yakir,
>
> On Wed, Jul 13, 2016 at 9:15 PM, Yakir Yang <ykk@rock-chips.com> wrote:
>> +static void psr_set_state(struct psr_drv *psr, enum psr_state state)
>> +{
>> +       mutex_lock(&psr->state_mutex);
>> +
>> +       if (psr->state == state) {
>> +               mutex_unlock(&psr->state_mutex);
>> +               return;
>> +       }
>> +
>> +       psr->state = state;
>> +       switch (state) {
>> +       case PSR_ENABLE:
>> +               psr->set(psr->encoder, true);
>> +               break;
>> +
>> +       case PSR_DISABLE:
>> +       case PSR_FLUSH:
>> +               psr->set(psr->encoder, false);
>> +               break;
>> +       };
>> +
>> +       mutex_unlock(&psr->state_mutex);
>> +}
>> +
>> +static void psr_flush_handler(unsigned long data)
>> +{
>> +       struct psr_drv *psr = (struct psr_drv *)data;
>> +
>> +       if (!psr || psr->state != PSR_FLUSH)
>> +               return;
>> +
>> +       psr_set_state(psr, PSR_ENABLE);
> As mentioned in a separate thread, this is probably not OK.
> psr_set_state() grabs a mutex and that might sleep.  ...but
> psr_flush_handler() is a timer.  I'm nearly certain that timers can't
> sleep.
>
> I believe this is the source of "sleeping function called from invalid
> context" that I've seen at times.

Thanks for your reported, i have wrote a patch[0] to fix this problem in 
my v5. If you're happy to review, that would be great ;)

[0]: https://patchwork.kernel.org/patch/9244805/

- Yakir

>
> -Doug
>
>
>