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

["Souza, Jose" <jose.souza@intel.com>]

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

> 
> > 
> > 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@intel.com>
> > Reported-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@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);
> > +		}
> >  	}
> >  }
> >  
>