[PATCH 35/45] drm/msm/dp: add a mst session mutex to protect bridge ops

[Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>]

To protect against concurrent access of the dp mst bridges
introduce a session mutex.

Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
---
 drivers/gpu/drm/msm/dp/dp_mst_drm.c | 20 ++++++++++++++++++++
 drivers/gpu/drm/msm/dp/dp_mst_drm.h |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_mst_drm.c b/drivers/gpu/drm/msm/dp/dp_mst_drm.c
index 15c61fd37c418889074222c0f576778adadf51c9..313eb63b9a35cbbb36db2d7d8f0a85e4441f2998 100644
--- a/drivers/gpu/drm/msm/dp/dp_mst_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_mst_drm.c
@@ -344,6 +344,7 @@ static void msm_dp_mst_bridge_atomic_pre_enable(struct drm_bridge *drm_bridge,
 	struct msm_dp_mst_bridge *bridge;
 	struct msm_dp *dp;
 	struct msm_dp_mst_bridge_state *msm_dp_bridge_state;
+	struct msm_dp_mst *dp_mst;
 
 	if (!drm_bridge) {
 		DRM_ERROR("Invalid params\n");
@@ -353,6 +354,7 @@ static void msm_dp_mst_bridge_atomic_pre_enable(struct drm_bridge *drm_bridge,
 	bridge = to_msm_dp_mst_bridge(drm_bridge);
 	msm_dp_bridge_state = to_msm_dp_mst_bridge_state(bridge);
 	dp = bridge->display;
+	dp_mst = dp->msm_dp_mst;
 
 	/* to cover cases of bridge_disable/bridge_enable without modeset */
 	bridge->connector = msm_dp_bridge_state->connector;
@@ -363,12 +365,14 @@ static void msm_dp_mst_bridge_atomic_pre_enable(struct drm_bridge *drm_bridge,
 		return;
 	}
 
+	mutex_lock(&dp_mst->mst_lock);
 	msm_dp_display_atomic_prepare(dp);
 
 	rc = _msm_dp_mst_bridge_pre_enable_part1(bridge, old_bridge_state);
 	if (rc) {
 		DRM_ERROR("[%d] DP display pre-enable failed, rc=%d\n", bridge->id, rc);
 		msm_dp_display_unprepare(dp);
+		mutex_unlock(&dp_mst->mst_lock);
 		return;
 	}
 
@@ -381,6 +385,8 @@ static void msm_dp_mst_bridge_atomic_pre_enable(struct drm_bridge *drm_bridge,
 		   drm_mode_vrefresh(&bridge->drm_mode),
 		   bridge->vcpi, bridge->start_slot,
 		   bridge->start_slot + bridge->num_slots);
+
+	mutex_unlock(&dp_mst->mst_lock);
 }
 
 static void msm_dp_mst_bridge_atomic_disable(struct drm_bridge *drm_bridge,
@@ -388,6 +394,7 @@ static void msm_dp_mst_bridge_atomic_disable(struct drm_bridge *drm_bridge,
 {
 	struct msm_dp_mst_bridge *bridge;
 	struct msm_dp *dp;
+	struct msm_dp_mst *mst;
 
 	if (!drm_bridge) {
 		DRM_ERROR("Invalid params\n");
@@ -401,6 +408,9 @@ static void msm_dp_mst_bridge_atomic_disable(struct drm_bridge *drm_bridge,
 	}
 
 	dp = bridge->display;
+	mst = dp->msm_dp_mst;
+
+	mutex_lock(&mst->mst_lock);
 
 	_msm_dp_mst_bridge_pre_disable_part1(bridge, old_bridge_state);
 
@@ -410,6 +420,8 @@ static void msm_dp_mst_bridge_atomic_disable(struct drm_bridge *drm_bridge,
 
 	drm_dbg_dp(dp->drm_dev, "mst bridge:%d conn:%d disable complete\n", bridge->id,
 		   DP_MST_CONN_ID(bridge));
+
+	mutex_unlock(&mst->mst_lock);
 }
 
 static void msm_dp_mst_bridge_atomic_post_disable(struct drm_bridge *drm_bridge,
@@ -418,6 +430,7 @@ static void msm_dp_mst_bridge_atomic_post_disable(struct drm_bridge *drm_bridge,
 	int conn = 0;
 	struct msm_dp_mst_bridge *bridge;
 	struct msm_dp *dp;
+	struct msm_dp_mst *mst;
 
 	if (!drm_bridge) {
 		DRM_ERROR("Invalid params\n");
@@ -433,6 +446,9 @@ static void msm_dp_mst_bridge_atomic_post_disable(struct drm_bridge *drm_bridge,
 	conn = DP_MST_CONN_ID(bridge);
 
 	dp = bridge->display;
+	mst = dp->msm_dp_mst;
+
+	mutex_lock(&mst->mst_lock);
 
 	msm_dp_display_atomic_post_disable_helper(dp, bridge->msm_dp_panel);
 
@@ -444,6 +460,8 @@ static void msm_dp_mst_bridge_atomic_post_disable(struct drm_bridge *drm_bridge,
 
 	drm_dbg_dp(dp->drm_dev, "mst bridge:%d conn:%d post disable complete\n",
 		   bridge->id, conn);
+
+	mutex_unlock(&mst->mst_lock);
 }
 
 static void msm_dp_mst_bridge_mode_set(struct drm_bridge *drm_bridge,
@@ -1072,6 +1090,8 @@ int msm_dp_mst_init(struct msm_dp *dp_display, u32 max_streams, u32 max_dpcd_tra
 
 	dp_display->msm_dp_mst = msm_dp_mst;
 
+	mutex_init(&msm_dp_mst->mst_lock);
+
 	msm_dp_mst->mst_initialized = true;
 
 	drm_dbg_dp(dp_display->drm_dev, "dp drm mst topology manager init completed\n");
diff --git a/drivers/gpu/drm/msm/dp/dp_mst_drm.h b/drivers/gpu/drm/msm/dp/dp_mst_drm.h
index 5fe5dc7596086467e9a3b3d7d04a665853fbb3d7..b1adb8a61115d4809107553809206bb2ed3c6c3d 100644
--- a/drivers/gpu/drm/msm/dp/dp_mst_drm.h
+++ b/drivers/gpu/drm/msm/dp/dp_mst_drm.h
@@ -80,6 +80,7 @@ struct msm_dp_mst {
 	struct drm_dp_aux *dp_aux;
 	bool mst_session_hpd_state;
 	u32 max_streams;
+	struct mutex mst_lock;
 };
 
 struct msm_dp_mst_connector {

-- 
2.34.1