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Commit e6b8fc0d authored by Pawan Kumar's avatar Pawan Kumar
Browse files

msm: mdss: Fix race condition for vsync irq enable/disable 



Disable and enable of vsync happens in separate thread, which
may lead to a race condition where enable/disable may
happen at the same time and resulting irq in disable state.
Add lock to properly synchronize the enabling/disabling
of vsync interrupts to fix race condition.

Change-Id: Ib52bea5ca7a3612c866a4a962f09725a77e40563
Signed-off-by: default avatarPawan Kumar <pavaku@codeaurora.org>
parent e1a9092b

drivers/video/msm/mdss/mdss_mdp_intf_video.c

+6 −0
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ struct mdss_mdp_video_ctx { 


	atomic_t vsync_ref;

	spinlock_t vsync_lock;

	struct mutex vsync_mtx;

	struct list_head vsync_handlers;

};
@@ -216,19 +217,23 @@ static inline void video_vsync_irq_enable(struct mdss_mdp_ctl *ctl, bool clear) 
{

	struct mdss_mdp_video_ctx *ctx = ctl->priv_data;



	mutex_lock(&ctx->vsync_mtx);

	if (atomic_inc_return(&ctx->vsync_ref) == 1)

		mdss_mdp_irq_enable(MDSS_MDP_IRQ_INTF_VSYNC, ctl->intf_num);

	else if (clear)

		mdss_mdp_irq_clear(ctl->mdata, MDSS_MDP_IRQ_INTF_VSYNC,

				ctl->intf_num);

	mutex_unlock(&ctx->vsync_mtx);

}



static inline void video_vsync_irq_disable(struct mdss_mdp_ctl *ctl)

{

	struct mdss_mdp_video_ctx *ctx = ctl->priv_data;



	mutex_lock(&ctx->vsync_mtx);

	if (atomic_dec_return(&ctx->vsync_ref) == 0)

		mdss_mdp_irq_disable(MDSS_MDP_IRQ_INTF_VSYNC, ctl->intf_num);

	mutex_unlock(&ctx->vsync_mtx);

}



static int mdss_mdp_video_add_vsync_handler(struct mdss_mdp_ctl *ctl,
@@ -687,6 +692,7 @@ int mdss_mdp_video_start(struct mdss_mdp_ctl *ctl) 
	ctx->intf_type = ctl->intf_type;

	init_completion(&ctx->vsync_comp);

	spin_lock_init(&ctx->vsync_lock);

	mutex_init(&ctx->vsync_mtx);

	atomic_set(&ctx->vsync_ref, 0);



	mdss_mdp_set_intr_callback(MDSS_MDP_IRQ_INTF_VSYNC, ctl->intf_num,