Merge tag 'topic/mst-fixes-2015-08-04' of git://anongit.freedesktop.org/drm-intel

Pull drm mst fixes from Daniel Vetter:
 "Special pull request for mst fixes since most of the patches touch
  code outside of i915 proper.  DRM parts have also been reviewed by
  Thierry (nvidia) since Dave's enjoying vacations"

* tag 'topic/mst-fixes-2015-08-04' of git://anongit.freedesktop.org/drm-intel:
  drm/atomic-helpers: Make encoder picking more robust
  drm/dp-mst: Remove debug WARN_ON
  drm/i915: Fixup dp mst encoder selection
  drm/atomic-helper: Add an atomice best_encoder callback

drivers/gpu/drm/drm_atomic_helper.c

@@ -196,6 +196,11 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx)
 	}
 
 	funcs = connector->helper_private;
+
+	if (funcs->atomic_best_encoder)
+		new_encoder = funcs->atomic_best_encoder(connector,
+							 connector_state);
+	else
 		new_encoder = funcs->best_encoder(connector);
 
 	if (!new_encoder) {
@@ -229,13 +234,14 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx)
 		}
 	}
 
+	if (WARN_ON(!connector_state->crtc))
+		return -EINVAL;
+
 	connector_state->best_encoder = new_encoder;
-	if (connector_state->crtc) {
 	idx = drm_crtc_index(connector_state->crtc);
 
 	crtc_state = state->crtc_states[idx];
 	crtc_state->mode_changed = true;
-	}
 
 	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d]\n",
 			 connector->base.id,

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -1294,7 +1294,6 @@ static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr,
 				goto retry;
 			}
 			DRM_DEBUG_KMS("failed to dpcd write %d %d\n", tosend, ret);
-			WARN(1, "fail\n");
 
 			return -EIO;
 		}

drivers/gpu/drm/i915/intel_dp_mst.c

@@ -357,6 +357,16 @@ intel_dp_mst_mode_valid(struct drm_connector *connector,
 	return MODE_OK;
 }
 
+static struct drm_encoder *intel_mst_atomic_best_encoder(struct drm_connector *connector,
+							 struct drm_connector_state *state)
+{
+	struct intel_connector *intel_connector = to_intel_connector(connector);
+	struct intel_dp *intel_dp = intel_connector->mst_port;
+	struct intel_crtc *crtc = to_intel_crtc(state->crtc);
+
+	return &intel_dp->mst_encoders[crtc->pipe]->base.base;
+}
+
 static struct drm_encoder *intel_mst_best_encoder(struct drm_connector *connector)
 {
 	struct intel_connector *intel_connector = to_intel_connector(connector);
@@ -367,6 +377,7 @@ static struct drm_encoder *intel_mst_best_encoder(struct drm_connector *connecto
 static const struct drm_connector_helper_funcs intel_dp_mst_connector_helper_funcs = {
 	.get_modes = intel_dp_mst_get_modes,
 	.mode_valid = intel_dp_mst_mode_valid,
+	.atomic_best_encoder = intel_mst_atomic_best_encoder,
 	.best_encoder = intel_mst_best_encoder,
 };
 

include/drm/drm_crtc_helper.h

@@ -168,6 +168,7 @@ struct drm_encoder_helper_funcs {
  * @get_modes: get mode list for this connector
  * @mode_valid: is this mode valid on the given connector? (optional)
  * @best_encoder: return the preferred encoder for this connector
+ * @atomic_best_encoder: atomic version of @best_encoder
  *
  * The helper operations are called by the mid-layer CRTC helper.
  */
@@ -176,6 +177,8 @@ struct drm_connector_helper_funcs {
 	enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
 					   struct drm_display_mode *mode);
 	struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
+	struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
+						   struct drm_connector_state *connector_state);
 };
 
 extern void drm_helper_disable_unused_functions(struct drm_device *dev);