drm/i915/psr: Modify intel_dp_get_su_granularity to support panel replay

Currently intel_dp_get_su_granularity doesn't support panel replay.
This fix modifies it to support panel replay as well.

v4:
  - use drm_dp_dpcd_readb instead of drm_dp_dpcd_read
  - ensure return value is 0 if drm_dp_dpcd_readb fails
v3: use correct offset for DP_PANEL_PANEL_REPLAY_CAPABILITY
v2: rely on PSR definitions on common bits
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240510093823.3146455-8-jouni.hogander@intel.com

drivers/gpu/drm/i915/display/intel_psr.c

@@ -468,6 +468,40 @@ static u8 intel_dp_get_sink_sync_latency(struct intel_dp *intel_dp)
 	return val;
 }
 
+static u8 intel_dp_get_su_capability(struct intel_dp *intel_dp)
+{
+	u8 su_capability = 0;
+
+	if (intel_dp->psr.sink_panel_replay_su_support)
+		drm_dp_dpcd_readb(&intel_dp->aux,
+				  DP_PANEL_PANEL_REPLAY_CAPABILITY,
+				  &su_capability);
+	else
+		su_capability = intel_dp->psr_dpcd[1];
+
+	return su_capability;
+}
+
+static unsigned int
+intel_dp_get_su_x_granularity_offset(struct intel_dp *intel_dp)
+{
+	return intel_dp->psr.sink_panel_replay_su_support ?
+		DP_PANEL_PANEL_REPLAY_X_GRANULARITY :
+		DP_PSR2_SU_X_GRANULARITY;
+}
+
+static unsigned int
+intel_dp_get_su_y_granularity_offset(struct intel_dp *intel_dp)
+{
+	return intel_dp->psr.sink_panel_replay_su_support ?
+		DP_PANEL_PANEL_REPLAY_Y_GRANULARITY :
+		DP_PSR2_SU_Y_GRANULARITY;
+}
+
+/*
+ * Note: Bits related to granularity are same in panel replay and psr
+ * registers. Rely on PSR definitions on these "common" bits.
+ */
 static void intel_dp_get_su_granularity(struct intel_dp *intel_dp)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
@@ -475,18 +509,29 @@ static void intel_dp_get_su_granularity(struct intel_dp *intel_dp)
 	u16 w;
 	u8 y;
 
-	/* If sink don't have specific granularity requirements set legacy ones */
-	if (!(intel_dp->psr_dpcd[1] & DP_PSR2_SU_GRANULARITY_REQUIRED)) {
+	/*
+	 * TODO: Do we need to take into account panel supporting both PSR and
+	 * Panel replay?
+	 */
+
+	/*
+	 * If sink don't have specific granularity requirements set legacy
+	 * ones.
+	 */
+	if (!(intel_dp_get_su_capability(intel_dp) &
+	      DP_PSR2_SU_GRANULARITY_REQUIRED)) {
 		/* As PSR2 HW sends full lines, we do not care about x granularity */
 		w = 4;
 		y = 4;
 		goto exit;
 	}
 
-	r = drm_dp_dpcd_read(&intel_dp->aux, DP_PSR2_SU_X_GRANULARITY, &w, 2);
+	r = drm_dp_dpcd_read(&intel_dp->aux,
+			     intel_dp_get_su_x_granularity_offset(intel_dp),
+			     &w, 2);
 	if (r != 2)
 		drm_dbg_kms(&i915->drm,
-			    "Unable to read DP_PSR2_SU_X_GRANULARITY\n");
+			    "Unable to read selective update x granularity\n");
 	/*
 	 * Spec says that if the value read is 0 the default granularity should
 	 * be used instead.
@@ -494,10 +539,12 @@ static void intel_dp_get_su_granularity(struct intel_dp *intel_dp)
 	if (r != 2 || w == 0)
 		w = 4;
 
-	r = drm_dp_dpcd_read(&intel_dp->aux, DP_PSR2_SU_Y_GRANULARITY, &y, 1);
+	r = drm_dp_dpcd_read(&intel_dp->aux,
+			     intel_dp_get_su_y_granularity_offset(intel_dp),
+			     &y, 1);
 	if (r != 1) {
 		drm_dbg_kms(&i915->drm,
-			    "Unable to read DP_PSR2_SU_Y_GRANULARITY\n");
+			    "Unable to read selective update y granularity\n");
 		y = 4;
 	}
 	if (y == 0)
@@ -590,7 +637,8 @@ void intel_psr_init_dpcd(struct intel_dp *intel_dp)
 	if (intel_dp->psr_dpcd[0])
 		_psr_init_dpcd(intel_dp);
 
-	if (intel_dp->psr.sink_psr2_support)
+	if (intel_dp->psr.sink_psr2_support ||
+	    intel_dp->psr.sink_panel_replay_su_support)
 		intel_dp_get_su_granularity(intel_dp);
 }