drm/i915/display: Always enables MST master pipe first

Due to DDB overlaps the pipe enabling sequence is not always crescent.
As the previous patch selects the smallest pipe/transcoder in the MST
stream to be master and it needs to be enabled first, this changes
were needed to guarantee that.

So first lets enable all pipes that do not need a fullmodeset as
those don't have any external dependency and those are the ones that
can overlap with each other.

Then on the second loop it will enable all the pipes that needs a
modeset and don't depends on other pipes like MST master
pipe/transcoder.

Then finally all the pipes that needs a modeset and have dependency
on other pipes, that at this point are alread enabled.

v3: rebased

v4:
- added check for modeset_pipes too to decide if is necessary for a
wait a vblank
- added DDB allocation overlap check for pipes that needs a modeset

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191223010654.67037-3-jose.souza@intel.com

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

@@ -14777,15 +14777,21 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
 	u8 hw_enabled_slices = dev_priv->wm.skl_hw.ddb.enabled_slices;
 	u8 required_slices = state->wm_results.ddb.enabled_slices;
 	struct skl_ddb_entry entries[I915_MAX_PIPES] = {};
-	u8 dirty_pipes = 0;
+	const u8 num_pipes = INTEL_NUM_PIPES(dev_priv);
+	u8 update_pipes = 0, modeset_pipes = 0;
 	int i;
 
 	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+		if (!new_crtc_state->hw.active)
+			continue;
+
 		/* ignore allocations for crtc's that have been turned off. */
-		if (!needs_modeset(new_crtc_state) && new_crtc_state->hw.active)
+		if (!needs_modeset(new_crtc_state)) {
 			entries[i] = old_crtc_state->wm.skl.ddb;
-		if (new_crtc_state->hw.active)
-			dirty_pipes |= BIT(crtc->pipe);
+			update_pipes |= BIT(crtc->pipe);
+		} else {
+			modeset_pipes |= BIT(crtc->pipe);
+		}
 	}
 
 	/* If 2nd DBuf slice required, enable it here */
@@ -14795,38 +14801,29 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
 	/*
 	 * Whenever the number of active pipes changes, we need to make sure we
 	 * update the pipes in the right order so that their ddb allocations
-	 * never overlap with eachother inbetween CRTC updates. Otherwise we'll
+	 * never overlap with each other between CRTC updates. Otherwise we'll
 	 * cause pipe underruns and other bad stuff.
+	 *
+	 * So first lets enable all pipes that do not need a fullmodeset as
+	 * those don't have any external dependency.
 	 */
-	while (dirty_pipes) {
+	while (update_pipes) {
 		for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
 						    new_crtc_state, i) {
 			enum pipe pipe = crtc->pipe;
-			bool modeset = needs_modeset(new_crtc_state);
 
-			if ((dirty_pipes & BIT(pipe)) == 0)
+			if ((update_pipes & BIT(pipe)) == 0)
 				continue;
 
 			if (skl_ddb_allocation_overlaps(&new_crtc_state->wm.skl.ddb,
-							entries,
-							INTEL_NUM_PIPES(dev_priv), i))
+							entries, num_pipes, i))
 				continue;
 
 			entries[i] = new_crtc_state->wm.skl.ddb;
-			dirty_pipes &= ~BIT(pipe);
+			update_pipes &= ~BIT(pipe);
 
-			if (modeset && is_trans_port_sync_mode(new_crtc_state)) {
-				if (is_trans_port_sync_master(new_crtc_state))
-					intel_update_trans_port_sync_crtcs(crtc,
-									   state,
-									   old_crtc_state,
-									   new_crtc_state);
-				else
-					continue;
-			} else {
 			intel_update_crtc(crtc, state, old_crtc_state,
 					  new_crtc_state);
-			}
 
 			/*
 			 * If this is an already active pipe, it's DDB changed,
@@ -14836,11 +14833,72 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
 			 */
 			if (!skl_ddb_entry_equal(&new_crtc_state->wm.skl.ddb,
 						 &old_crtc_state->wm.skl.ddb) &&
-			    !modeset && dirty_pipes)
+			    (update_pipes | modeset_pipes))
 				intel_wait_for_vblank(dev_priv, pipe);
 		}
 	}
 
+	/*
+	 * Enable all pipes that needs a modeset and do not depends on other
+	 * pipes
+	 */
+	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
+					    new_crtc_state, i) {
+		enum pipe pipe = crtc->pipe;
+
+		if ((modeset_pipes & BIT(pipe)) == 0)
+			continue;
+
+		if (intel_dp_mst_is_slave_trans(new_crtc_state) ||
+		    is_trans_port_sync_slave(new_crtc_state))
+			continue;
+
+		WARN_ON(skl_ddb_allocation_overlaps(&new_crtc_state->wm.skl.ddb,
+						    entries, num_pipes, i));
+
+		entries[i] = new_crtc_state->wm.skl.ddb;
+		modeset_pipes &= ~BIT(pipe);
+
+		if (is_trans_port_sync_mode(new_crtc_state)) {
+			struct intel_crtc *slave_crtc;
+
+			intel_update_trans_port_sync_crtcs(crtc, state,
+							   old_crtc_state,
+							   new_crtc_state);
+
+			slave_crtc = intel_get_slave_crtc(new_crtc_state);
+			/* TODO: update entries[] of slave */
+			modeset_pipes &= ~BIT(slave_crtc->pipe);
+
+		} else {
+			intel_update_crtc(crtc, state, old_crtc_state,
+					  new_crtc_state);
+		}
+	}
+
+	/*
+	 * Finally enable all pipes that needs a modeset and depends on
+	 * other pipes, right now it is only MST slaves as both port sync slave
+	 * and master are enabled together
+	 */
+	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
+					    new_crtc_state, i) {
+		enum pipe pipe = crtc->pipe;
+
+		if ((modeset_pipes & BIT(pipe)) == 0)
+			continue;
+
+		WARN_ON(skl_ddb_allocation_overlaps(&new_crtc_state->wm.skl.ddb,
+						    entries, num_pipes, i));
+
+		entries[i] = new_crtc_state->wm.skl.ddb;
+		modeset_pipes &= ~BIT(pipe);
+
+		intel_update_crtc(crtc, state, old_crtc_state, new_crtc_state);
+	}
+
+	WARN_ON(modeset_pipes);
+
 	/* If 2nd DBuf slice is no more required disable it */
 	if (INTEL_GEN(dev_priv) >= 11 && required_slices < hw_enabled_slices)
 		icl_dbuf_slices_update(dev_priv, required_slices);