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

[Jouni Högander]

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.

Fix this by checking if old and new crtc encoder masks are differing.
PSR is disabled for encoders not in new crtc state encoder mask.

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>
---
 drivers/gpu/drm/i915/display/intel_psr.c | 72 +++++++++++++++++-------
 1 file changed, 51 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index e6a870641cd2..710cc31ace22 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -1863,36 +1863,66 @@ 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_crtc_state *new_crtc_state, *old_crtc_state;
 	struct intel_encoder *encoder;
+	struct intel_dp *intel_dp;
+	struct intel_psr *psr;
+	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;
-
-		mutex_lock(&psr->lock);
-
+	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
+					    new_crtc_state, i) {
 		/*
-		 * Reasons to disable:
-		 * - PSR disabled in new state
-		 * - All planes will go inactive
-		 * - Changing between PSR versions
+		 * Check if encoder exists in new state and disable
+		 * psr if it doesn't. Otherwise we will end update
+		 * having all planes disabled and psr enabled which
+		 * seems to be causing problems.
 		 */
-		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;
+		if (old_crtc_state->uapi.encoder_mask != new_crtc_state->uapi.encoder_mask) {
+			for_each_intel_encoder_mask_with_psr(state->base.dev, encoder,
+							     old_crtc_state->uapi.encoder_mask) {
+				intel_dp = enc_to_intel_dp(encoder);
+				psr = &intel_dp->psr;
 
-		if (psr->enabled && needs_to_disable)
-			intel_psr_disable_locked(intel_dp);
+				if (new_crtc_state->uapi.encoder_mask &
+				    drm_encoder_mask(&(encoder)->base))
+					continue;
 
-		mutex_unlock(&psr->lock);
+				mutex_lock(&psr->lock);
+
+				if (psr->enabled)
+					intel_psr_disable_locked(intel_dp);
+
+				mutex_unlock(&psr->lock);
+			}
+		}
+		for_each_intel_encoder_mask_with_psr(state->base.dev, encoder,
+						     new_crtc_state->uapi.encoder_mask) {
+			bool needs_to_disable = false;
+
+			intel_dp = enc_to_intel_dp(encoder);
+			psr = &intel_dp->psr;
+
+			mutex_lock(&psr->lock);
+
+			/*
+			 * Reasons to disable:
+			 * - PSR disabled in new state
+			 * - All planes will go inactive
+			 * - Changing between PSR versions
+			 */
+			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;
+
+			if (psr->enabled && needs_to_disable)
+				intel_psr_disable_locked(intel_dp);
+
+			mutex_unlock(&psr->lock);
+		}
 	}
 }
 
-- 
2.25.1