1 files changed, 85 insertions, 12 deletions

diff --git a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_mixer.c b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_mixer.c
index 9bb1f82..8a00991 100644
--- a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_mixer.c
+++ b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_mixer.c
@@ -16,42 +16,115 @@
 
 #include "mdp5_kms.h"
 
-struct mdp5_hw_mixer *mdp5_mixer_assign(struct drm_atomic_state *s,
-					struct drm_crtc *crtc, uint32_t caps)
+/*
+ * As of now, there are only 2 combinations possible for source split:
+ *
+ * Left | Right
+ * -----|------
+ *  LM0 | LM1
+ *  LM2 | LM5
+ *
+ */
+static int lm_right_pair[] = { 1, -1, 5, -1, -1, -1 };
+
+static int get_right_pair_idx(struct mdp5_kms *mdp5_kms, int lm)
+{
+	int i;
+	int pair_lm;
+
+	pair_lm = lm_right_pair[lm];
+	if (pair_lm < 0)
+		return -EINVAL;
+
+	for (i = 0; i < mdp5_kms->num_hwmixers; i++) {
+		struct mdp5_hw_mixer *mixer = mdp5_kms->hwmixers[i];
+
+		if (mixer->lm == pair_lm)
+			return mixer->idx;
+	}
+
+	return -1;
+}
+
+int mdp5_mixer_assign(struct drm_atomic_state *s, struct drm_crtc *crtc,
+		      uint32_t caps, struct mdp5_hw_mixer **mixer,
+		      struct mdp5_hw_mixer **r_mixer)
 {
 	struct msm_drm_private *priv = s->dev->dev_private;
 	struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(priv->kms));
 	struct mdp5_state *state = mdp5_get_state(s);
 	struct mdp5_hw_mixer_state *new_state;
-	struct mdp5_hw_mixer *mixer = NULL;
 	int i;
 
 	if (IS_ERR(state))
-		return ERR_CAST(state);
+		return PTR_ERR(state);
 
 	new_state = &state->hwmixer;
 
 	for (i = 0; i < mdp5_kms->num_hwmixers; i++) {
 		struct mdp5_hw_mixer *cur = mdp5_kms->hwmixers[i];
 
-		/* skip if already in-use */
-		if (new_state->hwmixer_to_crtc[cur->idx])
+		/*
+		 * skip if already in-use by a different CRTC. If there is a
+		 * mixer already assigned to this CRTC, it means this call is
+		 * a request to get an additional right mixer. Assume that the
+		 * existing mixer is the 'left' one, and try to see if we can
+		 * get its corresponding 'right' pair.
+		 */
+		if (new_state->hwmixer_to_crtc[cur->idx] &&
+		    new_state->hwmixer_to_crtc[cur->idx] != crtc)
 			continue;
 
 		/* skip if doesn't support some required caps: */
 		if (caps & ~cur->caps)
 			continue;
 
-		if (!mixer)
-			mixer = cur;
+		if (r_mixer) {
+			int pair_idx;
+
+			pair_idx = get_right_pair_idx(mdp5_kms, cur->lm);
+			if (pair_idx < 0)
+				return -EINVAL;
+
+			if (new_state->hwmixer_to_crtc[pair_idx])
+				continue;
+
+			*r_mixer = mdp5_kms->hwmixers[pair_idx];
+		}
+
+		/*
+		 * prefer a pair-able LM over an unpairable one. We can
+		 * switch the CRTC from Normal mode to Source Split mode
+		 * without requiring a full modeset if we had already
+		 * assigned this CRTC a pair-able LM.
+		 *
+		 * TODO: There will be assignment sequences which would
+		 * result in the CRTC requiring a full modeset, even
+		 * if we have the LM resources to prevent it. For a platform
+		 * with a few displays, we don't run out of pair-able LMs
+		 * so easily. For now, ignore the possibility of requiring
+		 * a full modeset.
+		 */
+		if (!(*mixer) || cur->caps & MDP_LM_CAP_PAIR)
+			*mixer = cur;
 	}
 
-	if (!mixer)
-		return ERR_PTR(-ENOMEM);
+	if (!(*mixer))
+		return -ENOMEM;
 
-	new_state->hwmixer_to_crtc[mixer->idx] = crtc;
+	if (r_mixer && !(*r_mixer))
+		return -ENOMEM;
 
-	return mixer;
+	DBG("assigning Layer Mixer %d to crtc %s", (*mixer)->lm, crtc->name);
+
+	new_state->hwmixer_to_crtc[(*mixer)->idx] = crtc;
+	if (r_mixer) {
+		DBG("assigning Right Layer Mixer %d to crtc %s", (*r_mixer)->lm,
+		    crtc->name);
+		new_state->hwmixer_to_crtc[(*r_mixer)->idx] = crtc;
+	}
+
+	return 0;
 }
 
 void mdp5_mixer_release(struct drm_atomic_state *s, struct mdp5_hw_mixer *mixer)