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

[Souza, Jose]

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?

> 
> 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);
> +		}
>  	}
>  }
>