[Intel-gfx] [PATCH] drm/i915/display/psr: Add sink not reliable check to intel_psr_work()

[Mun, Gwan-gyeong]

On Fri, 2021-03-12 at 05:37 -0800, Souza, Jose wrote:
> On Fri, 2021-03-12 at 15:34 +0200, Gwan-gyeong Mun wrote:
> > If the sink state is not reliable, it does not need to wait for
> > PSR "IDLE state" for re-enabling PSR. And it should not try to re-
> > enable
> > PSR.
> > 
> > Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_psr.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > b/drivers/gpu/drm/i915/display/intel_psr.c
> > index cd434285e3b7..7f555407de06 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -1686,6 +1686,9 @@ static void intel_psr_work(struct work_struct
> > *work)
> >         if (READ_ONCE(intel_dp->psr.irq_aux_error))
> >                 intel_psr_handle_irq(intel_dp);
> >  
> > 
> > 
> > 
1. In intel_psr_irq_handler()
   when the psr error happens,
     intel_dp->psr.irq_aux_error = true; 
      schedule_work(&intel_dp->psr.work);


2. In intel_psr_work()
    ...
   if (READ_ONCE(intel_dp->psr.irq_aux_error))
     intel_psr_handle_irq(intel_dp); 
	 -> intel_psr_disable_locked(intel_dp); 
            psr->sink_not_reliable = true;  
    ...


IMO, when this scenario happens, the below code seems to be needed.

> > +       if (intel_dp->psr.sink_not_reliable)
> > +               goto unlock;
> 
> I can't think any scenario that this will hit.
> Before set sink_not_reliable PSR will be disabled so it will be caught
> in the first check of intel_psr_work().
> 
> > +
> >         /*
> >          * We have to make sure PSR is ready for re-enable
> >          * otherwise it keeps disabled until next full enable/disable
> > cycle.
>