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

[Abhinav Kumar]

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

Signed-off-by: Abhinav Kumar <quic_abhin...@quicinc.com>
---
 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