disp: msm: sde: add vblank mutex lock during irq unregister

Currently, during ctl reset in video mode, irq register or
unregister might result in race condition with vblank
enable/disable calls on event thread resulting in enable
cnt mismatch. This change adds mutex locks to avoid race
conditions in such cases.

Change-Id: I45aef19864475ac1b02dd8e84810eee233fc60ea
Signed-off-by: Yashwanth <[email protected]>

msm/sde/sde_encoder_phys_vid.c

@@ -924,6 +924,7 @@ static int sde_encoder_phys_vid_prepare_for_kickoff(
 	struct drm_connector *conn;
 	int event;
 	int rc;
+	int irq_enable;
 
 	if (!phys_enc || !params || !phys_enc->hw_ctl) {
 		SDE_ERROR("invalid encoder/parameters\n");
@@ -952,12 +953,21 @@ static int sde_encoder_phys_vid_prepare_for_kickoff(
 		/* to avoid flooding, only log first time, and "dead" time */
 		if (vid_enc->error_count == 1) {
 			SDE_EVT32(DRMID(phys_enc->parent), SDE_EVTLOG_FATAL);
+			mutex_lock(phys_enc->vblank_ctl_lock);
 
-			sde_encoder_helper_unregister_irq(
+			irq_enable = atomic_read(&phys_enc->vblank_refcount);
+
+			if (irq_enable)
+				sde_encoder_helper_unregister_irq(
 					phys_enc, INTR_IDX_VSYNC);
+
 			SDE_DBG_DUMP("all", "dbg_bus", "vbif_dbg_bus");
-			sde_encoder_helper_register_irq(
+
+			if (irq_enable)
+				sde_encoder_helper_register_irq(
 					phys_enc, INTR_IDX_VSYNC);
+
+			mutex_unlock(phys_enc->vblank_ctl_lock);
 		}
 
 		/*