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disp: msm: dp: avoid use of mst_lock in hpd callbacks

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DP MST driver registers bridge callback functions with the DRM framework.
mst_lock is used for synchronization of the mst bridge functions. These
functions call into dp_display where a session lock is obtained for
the display. HPD callbacks, on the other hand, are first handled by
dp_display. During these callbacks, dp_display takes a session lock
first before calling into DP MST driver layer. Currently, the DP MST
layer waits on mst_lock which can result in a deadlock.

This change removes the usage of mst_lock inside hpd callback functions
and just uses the session lock for synchronization.

Change-Id: I7ec338004eef43ac0f1e1f092463e9915cd60684
Signed-off-by: Rajkumar Subbiah <rsubbia@codeaurora.org>
This commit is contained in:
Rajkumar Subbiah 2020-08-18 22:17:08 -04:00
commit b240ae79e4
1 changed files with 2 additions and 8 deletions
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10
msm/dp/dp_mst_drm.c
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@ -2163,11 +2163,8 @@ static int dp_mst_display_set_mgr_state(void *dp_display, bool state,
* on hpd_low, set_mgr_state is called after hotplug event is sent and
* the session_state was already updated prior to that.
*/
if (state) {
mutex_lock(&mst->mst_lock);
if (state)
mst->mst_session_state = state;
mutex_unlock(&mst->mst_lock);
}
if (info && !info->mst_protocol) {
if (state) {
@ -2201,11 +2198,8 @@ static void dp_mst_display_hpd(void *dp_display, bool hpd_status)
* session state should be unset here for the connection status to be
* updated accordingly.
*/
if (!hpd_status) {
mutex_lock(&mst->mst_lock);
if (!hpd_status)
mst->mst_session_state = hpd_status;
mutex_unlock(&mst->mst_lock);
}
dp_mst_hpd_event_notify(mst, hpd_status);
}