drm/i915/mst: Use .compute_config_late() to compute master transcoder

Use the recently introduced encoder .compute_config_late() hook to
do the MST master transcoder assignment. Avoids having to do it
in a funny way before we know the CPU transcoder of each pipe.

And now we can also properly use hw.active instead of uapi.active
since it too has been calculated earlier for everyone.

Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-2-ville.syrjala@linux.intel.comReviewed-by: José Roberto de Souza <jose.souza@intel.com>

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

@@ -90,56 +90,10 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
 	return 0;
 }
 
-/*
- * Iterate over all connectors and return the smallest transcoder in the MST
- * stream
- */
-static enum transcoder
-intel_dp_mst_master_trans_compute(struct intel_atomic_state *state,
-				  struct intel_dp *mst_port)
-{
-	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
-	struct intel_digital_connector_state *conn_state;
-	struct intel_connector *connector;
-	enum pipe ret = I915_MAX_PIPES;
-	int i;
-
-	if (INTEL_GEN(dev_priv) < 12)
-		return INVALID_TRANSCODER;
-
-	for_each_new_intel_connector_in_state(state, connector, conn_state, i) {
-		struct intel_crtc_state *crtc_state;
-		struct intel_crtc *crtc;
-
-		if (connector->mst_port != mst_port || !conn_state->base.crtc)
-			continue;
-
-		crtc = to_intel_crtc(conn_state->base.crtc);
-		crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
-		if (!crtc_state->uapi.active)
-			continue;
-
-		/*
-		 * Using crtc->pipe because crtc_state->cpu_transcoder is
-		 * computed, so others CRTCs could have non-computed
-		 * cpu_transcoder
-		 */
-		if (crtc->pipe < ret)
-			ret = crtc->pipe;
-	}
-
-	if (ret == I915_MAX_PIPES)
-		return INVALID_TRANSCODER;
-
-	/* Simple cast works because TGL don't have a eDP transcoder */
-	return (enum transcoder)ret;
-}
-
 static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 				       struct intel_crtc_state *pipe_config,
 				       struct drm_connector_state *conn_state)
 {
-	struct intel_atomic_state *state = to_intel_atomic_state(conn_state->state);
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
 	struct intel_dp *intel_dp = &intel_mst->primary->dp;
@@ -203,7 +157,56 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 
 	intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
 
-	pipe_config->mst_master_transcoder = intel_dp_mst_master_trans_compute(state, intel_dp);
+	return 0;
+}
+
+/*
+ * Iterate over all connectors and return a mask of
+ * all CPU transcoders streaming over the same DP link.
+ */
+static unsigned int
+intel_dp_mst_transcoder_mask(struct intel_atomic_state *state,
+			     struct intel_dp *mst_port)
+{
+	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
+	const struct intel_digital_connector_state *conn_state;
+	struct intel_connector *connector;
+	u8 transcoders = 0;
+	int i;
+
+	if (INTEL_GEN(dev_priv) < 12)
+		return 0;
+
+	for_each_new_intel_connector_in_state(state, connector, conn_state, i) {
+		const struct intel_crtc_state *crtc_state;
+		struct intel_crtc *crtc;
+
+		if (connector->mst_port != mst_port || !conn_state->base.crtc)
+			continue;
+
+		crtc = to_intel_crtc(conn_state->base.crtc);
+		crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
+
+		if (!crtc_state->hw.active)
+			continue;
+
+		transcoders |= BIT(crtc_state->cpu_transcoder);
+	}
+
+	return transcoders;
+}
+
+static int intel_dp_mst_compute_config_late(struct intel_encoder *encoder,
+					    struct intel_crtc_state *crtc_state,
+					    struct drm_connector_state *conn_state)
+{
+	struct intel_atomic_state *state = to_intel_atomic_state(conn_state->state);
+	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
+	struct intel_dp *intel_dp = &intel_mst->primary->dp;
+
+	/* lowest numbered transcoder will be designated master */
+	crtc_state->mst_master_transcoder =
+		ffs(intel_dp_mst_transcoder_mask(state, intel_dp)) - 1;
 
 	return 0;
 }
@@ -822,6 +825,7 @@ intel_dp_create_fake_mst_encoder(struct intel_digital_port *intel_dig_port, enum
 	intel_encoder->pipe_mask = ~0;
 
 	intel_encoder->compute_config = intel_dp_mst_compute_config;
+	intel_encoder->compute_config_late = intel_dp_mst_compute_config_late;
 	intel_encoder->disable = intel_mst_disable_dp;
 	intel_encoder->post_disable = intel_mst_post_disable_dp;
 	intel_encoder->pre_pll_enable = intel_mst_pre_pll_enable_dp;