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

[Yakir Yang]

Doug,

On 07/23/2016 12:04 PM, Doug Anderson wrote:
> Yakir,
>
> On Wed, Jul 13, 2016 at 9:15 PM, Yakir Yang <ykk@xxxxxxxxxxxxxx> 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