[Intel-gfx] [PATCH v2] drm/i915/display: Ensure PSR gets disabled if no encoders in new state

[Hogander, Jouni]

On Wed, 2022-07-13 at 21:04 +0000, Souza, Jose wrote:
> On Wed, 2022-07-13 at 20:58 +0000, Souza, Jose wrote:
> > On Mon, 2022-07-11 at 14:17 +0300, Jouni Högander wrote:
> > > Currently PSR is left enabled when all planes are disabled if
> > > there
> > > is no attached encoder in new state. This seems to be causing
> > > FIFO
> > > underruns.
> > 
> > What is the case were there is no attached encoder and
> > active_planes > 0?
> 
> Can you point to some test?

You just need to run kms_busy at basic and this triggers when dynamic
subtest modeset is run.

> I believe that a pipe to be enabled needs to have a enconder/port
> attached, otherwise it will be disabled.

To my understanding pipe actually gets eventually disabled in this
testcase as well. Before pipe is disabled we have state where planes
are all disabled, but PSR is kept enabled. This was triggering FIFO
underrun.

> 
> > > Fix this by checking if encoder exists in new crtc state and
> > > disable
> > > PSR if it doesn't.
> > > 
> > > v2: Unify disable logic with existing
> > > 
> > > Cc: Mika Kahola <mika.kahola at intel.com>
> > > Reported-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> > > Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
> > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com
> > > >
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_psr.c | 53 ++++++++++++++--
> > > --------
> > >  1 file changed, 31 insertions(+), 22 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > > b/drivers/gpu/drm/i915/display/intel_psr.c
> > > index e6a870641cd2..90599dd1cb1b 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > > @@ -1863,36 +1863,45 @@ void intel_psr_pre_plane_update(struct
> > > intel_atomic_state *state,
> > >  struct intel_crtc *crtc)
> > >  {
> > >  struct drm_i915_private *i915 = to_i915(state->base.dev);
> > > -const struct intel_crtc_state *crtc_state =
> > > -intel_atomic_get_new_crtc_state(state, crtc);
> > > -struct intel_encoder *encoder;
> > > +struct intel_crtc_state *new_crtc_state, *old_crtc_state;
> > > +int i;
> > > 
> > >  if (!HAS_PSR(i915))
> > >  return;
> > > 
> > > -for_each_intel_encoder_mask_with_psr(state->base.dev, encoder,
> > > -     crtc_state->uapi.encoder_mask) {
> > > -struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > -struct intel_psr *psr = &intel_dp->psr;
> > > -bool needs_to_disable = false;
> > > +for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
> > > +    new_crtc_state, i) {
> > > +struct intel_encoder *encoder;
> > > +u32 old_new_encoder_mask = old_crtc_state->uapi.encoder_mask |
> > > +new_crtc_state->uapi.encoder_mask;
> > > 
> > > -mutex_lock(&psr->lock);
> > > +for_each_intel_encoder_mask_with_psr(state->base.dev, encoder,
> > > +     old_new_encoder_mask) {
> > > +struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > +struct intel_psr *psr = &intel_dp->psr;
> > > +bool needs_to_disable = false;
> > > 
> > > -/*
> > > - * Reasons to disable:
> > > - * - PSR disabled in new state
> > > - * - All planes will go inactive
> > > - * - Changing between PSR versions
> > > - */
> > > -needs_to_disable |= intel_crtc_needs_modeset(crtc_state);
> > > -needs_to_disable |= !crtc_state->has_psr;
> > > -needs_to_disable |= !crtc_state->active_planes;
> > > -needs_to_disable |= crtc_state->has_psr2 != psr->psr2_enabled;
> > > +mutex_lock(&psr->lock);
> > > 
> > > -if (psr->enabled && needs_to_disable)
> > > -intel_psr_disable_locked(intel_dp);
> > > +/*
> > > + * Reasons to disable:
> > > + * - PSR disabled in new state
> > > + * - All planes will go inactive
> > > + * - Changing between PSR versions
> > > + * - Encoder isn't present in new mask
> > > + */
> > > +needs_to_disable |= intel_crtc_needs_modeset(new_crtc_state);
> > > +needs_to_disable |= !new_crtc_state->has_psr;
> > > +needs_to_disable |= !new_crtc_state->active_planes;
> > > +needs_to_disable |= new_crtc_state->has_psr2 != psr-
> > > >psr2_enabled;
> > > +needs_to_disable |= !(new_crtc_state->uapi.encoder_mask &
> > > +      drm_encoder_mask(&(encoder)->base));
> > > 
> > > -mutex_unlock(&psr->lock);
> > > +if (psr->enabled && needs_to_disable)
> > > +intel_psr_disable_locked(intel_dp);
> > > +
> > > +mutex_unlock(&psr->lock);
> > > +}
> > >  }
> > >  }
> > >