From 4fe4816a089217c8f024adbcd369bfa007f6d1ee Mon Sep 17 00:00:00 2001
From: Dhaval Patel <pdhaval@codeaurora.org>
Date: Tue, 1 Sep 2015 16:51:51 -0700
Subject: [PATCH] msm: mdss: fix race condition between dfps update and stop

Dynamic fps change and video interface stop works in two
different thread. It is possible that video interface move
to stop state when dynamic fps thread is in process of
updating the fps information on the same interface.

This change acquires the stop mutex lock and releases it
at the end.

Change-Id: I94d279ea53acb7daa7b042829c0e31df758a6782
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>
---
 drivers/video/fbdev/msm/mdss_mdp_intf_video.c | 36 ++++++++++---------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/video/fbdev/msm/mdss_mdp_intf_video.c b/drivers/video/fbdev/msm/mdss_mdp_intf_video.c
index 4bad0c382f58..d8c7dd91e97c 100644
--- a/drivers/video/fbdev/msm/mdss_mdp_intf_video.c
+++ b/drivers/video/fbdev/msm/mdss_mdp_intf_video.c
@@ -825,10 +825,6 @@ static int mdss_mdp_video_dfps_wait4vsync(struct mdss_mdp_ctl *ctl)
 	struct mdss_mdp_video_ctx *ctx;
 
 	ctx = (struct mdss_mdp_video_ctx *) ctl->intf_ctx[MASTER_CTX];
-	if (!ctx) {
-		pr_err("invalid ctx\n");
-		return -ENODEV;
-	}
 
 	video_vsync_irq_enable(ctl, true);
 	reinit_completion(&ctx->vsync_comp);
@@ -892,9 +888,9 @@ static int mdss_mdp_video_config_fps(struct mdss_mdp_ctl *ctl,
 	struct mdss_data_type *mdata;
 
 	ctx = (struct mdss_mdp_video_ctx *) ctl->intf_ctx[MASTER_CTX];
-	if (!ctx) {
-		pr_err("invalid ctx\n");
-		return -ENODEV;
+	if (!ctx || !ctx->timegen_en || !ctx->ref_cnt) {
+		pr_err("invalid ctx or interface is powered off\n");
+		return -EINVAL;
 	}
 
 	mdata = ctl->mdata;
@@ -906,22 +902,25 @@ static int mdss_mdp_video_config_fps(struct mdss_mdp_ctl *ctl,
 		}
 	} else if (is_pingpong_split(ctl->mfd)) {
 		sctx = (struct mdss_mdp_video_ctx *) ctl->intf_ctx[SLAVE_CTX];
-		if (!sctx) {
-			pr_err("invalid sctx\n");
-			return -ENODEV;
+		if (!sctx || !sctx->timegen_en || !sctx->ref_cnt) {
+			pr_err("invalid sctx or interface is powered off\n");
+			return -EINVAL;
 		}
 	}
 
+	mutex_lock(&ctl->offlock);
 	pdata = ctl->panel_data;
 	if (pdata == NULL) {
 		pr_err("%s: Invalid panel data\n", __func__);
-		return -EINVAL;
+		rc = -EINVAL;
+		goto end;
 	}
 
 	if (!pdata->panel_info.dynamic_fps) {
 		pr_err("%s: Dynamic fps not enabled for this panel\n",
 						__func__);
-		return -EINVAL;
+		rc = -EINVAL;
+		goto end;
 	}
 
 	vsync_period = mdss_panel_get_vtotal(&pdata->panel_info);
@@ -933,7 +932,8 @@ static int mdss_mdp_video_config_fps(struct mdss_mdp_ctl *ctl,
 				== DFPS_IMMEDIATE_CLK_UPDATE_MODE) {
 			if (!ctx->timegen_en) {
 				pr_err("TG is OFF. DFPS mode invalid\n");
-				return -EINVAL;
+				rc = -EINVAL;
+				goto end;
 			}
 			rc = mdss_mdp_ctl_intf_event(ctl,
 					MDSS_EVENT_PANEL_UPDATE_FPS,
@@ -948,7 +948,8 @@ static int mdss_mdp_video_config_fps(struct mdss_mdp_ctl *ctl,
 			unsigned long flags;
 			if (!ctx->timegen_en) {
 				pr_err("TG is OFF. DFPS mode invalid\n");
-				return -EINVAL;
+				rc = -EINVAL;
+				goto end;
 			}
 
 			/*
@@ -961,7 +962,7 @@ static int mdss_mdp_video_config_fps(struct mdss_mdp_ctl *ctl,
 			rc = mdss_mdp_video_dfps_wait4vsync(ctl);
 			if (rc < 0) {
 				pr_err("Error during wait4vsync\n");
-				return rc;
+				goto end;
 			}
 
 			mdss_mdp_clk_ctrl(MDP_BLOCK_POWER_ON);
@@ -1017,7 +1018,8 @@ exit_dfps:
 		} else {
 			pr_err("intf %d panel, unknown FPS mode\n",
 							ctl->intf_num);
-			return -EINVAL;
+			rc = -EINVAL;
+			goto end;
 		}
 	} else {
 		rc = mdss_mdp_ctl_intf_event(ctl,
@@ -1028,6 +1030,8 @@ exit_dfps:
 						ctl->intf_num, rc);
 	}
 
+end:
+	mutex_unlock(&ctl->offlock);
 	return rc;
 }