1 files changed, 49 insertions, 18 deletions

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index a9bb656058e5..1dbd1dcdcf15 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1123,17 +1123,21 @@ nv50_mstm_enable(struct nv50_mstm *mstm, u8 dpcd, int state)
 	int ret;
 
 	if (dpcd >= 0x12) {
-		ret = drm_dp_dpcd_readb(mstm->mgr.aux, DP_MSTM_CTRL, &dpcd);
+		/* Even if we're enabling MST, start with disabling the
+		 * branching unit to clear any sink-side MST topology state
+		 * that wasn't set by us
+		 */
+		ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL, 0);
 		if (ret < 0)
 			return ret;
 
-		dpcd &= ~DP_MST_EN;
-		if (state)
-			dpcd |= DP_MST_EN;
-
-		ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL, dpcd);
-		if (ret < 0)
-			return ret;
+		if (state) {
+			/* Now, start initializing */
+			ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL,
+						 DP_MST_EN);
+			if (ret < 0)
+				return ret;
+		}
 	}
 
 	return nvif_mthd(disp, 0, &args, sizeof(args));
@@ -1142,31 +1146,58 @@ nv50_mstm_enable(struct nv50_mstm *mstm, u8 dpcd, int state)
 int
 nv50_mstm_detect(struct nv50_mstm *mstm, u8 dpcd[8], int allow)
 {
-	int ret, state = 0;
+	struct drm_dp_aux *aux;
+	int ret;
+	bool old_state, new_state;
+	u8 mstm_ctrl;
 
 	if (!mstm)
 		return 0;
 
-	if (dpcd[0] >= 0x12) {
-		ret = drm_dp_dpcd_readb(mstm->mgr.aux, DP_MSTM_CAP, &dpcd[1]);
+	mutex_lock(&mstm->mgr.lock);
+
+	old_state = mstm->mgr.mst_state;
+	new_state = old_state;
+	aux = mstm->mgr.aux;
+
+	if (old_state) {
+		/* Just check that the MST hub is still as we expect it */
+		ret = drm_dp_dpcd_readb(aux, DP_MSTM_CTRL, &mstm_ctrl);
+		if (ret < 0 || !(mstm_ctrl & DP_MST_EN)) {
+			DRM_DEBUG_KMS("Hub gone, disabling MST topology\n");
+			new_state = false;
+		}
+	} else if (dpcd[0] >= 0x12) {
+		ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &dpcd[1]);
 		if (ret < 0)
-			return ret;
+			goto probe_error;
 
 		if (!(dpcd[1] & DP_MST_CAP))
 			dpcd[0] = 0x11;
 		else
-			state = allow;
+			new_state = allow;
+	}
+
+	if (new_state == old_state) {
+		mutex_unlock(&mstm->mgr.lock);
+		return new_state;
 	}
 
-	ret = nv50_mstm_enable(mstm, dpcd[0], state);
+	ret = nv50_mstm_enable(mstm, dpcd[0], new_state);
 	if (ret)
-		return ret;
+		goto probe_error;
+
+	mutex_unlock(&mstm->mgr.lock);
 
-	ret = drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, state);
+	ret = drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, new_state);
 	if (ret)
 		return nv50_mstm_enable(mstm, dpcd[0], 0);
 
-	return mstm->mgr.mst_state;
+	return new_state;
+
+probe_error:
+	mutex_unlock(&mstm->mgr.lock);
+	return ret;
 }
 
 static void
@@ -2074,7 +2105,7 @@ nv50_disp_atomic_state_alloc(struct drm_device *dev)
 static const struct drm_mode_config_funcs
 nv50_disp_func = {
 	.fb_create = nouveau_user_framebuffer_create,
-	.output_poll_changed = drm_fb_helper_output_poll_changed,
+	.output_poll_changed = nouveau_fbcon_output_poll_changed,
 	.atomic_check = nv50_disp_atomic_check,
 	.atomic_commit = nv50_disp_atomic_commit,
 	.atomic_state_alloc = nv50_disp_atomic_state_alloc,