[PATCH 1/3] drm/exynos: modify wait for vsync functions to use wait queues

[Prathyush K]

It is more optimium to use wait queues while waiting for vsync so
that the current task is put to sleep. This way, the task wont
hog the CPU while waiting. We use wait_event_timeout and not
an interruptible function since we dont want the function to exit
when a signal is pending (e.g. drm release). This patch modifies
the wait for vblank functions of both fimd and mixer.

Also, the current fimd wait_for_vblank did not work in exynos5
since VIDCON1 has to be used in addition to timing base offset
(0x20000). This patch also eliminates this problem.

Signed-off-by: Prathyush K <prathyush.k at samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_drv.h  |   14 --------------
 drivers/gpu/drm/exynos/exynos_drm_fimd.c |   21 +++++++++++++++++----
 drivers/gpu/drm/exynos/exynos_mixer.c    |   21 ++++++++++++++++-----
 3 files changed, 33 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h
index a4702a8..6bb8644 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h
@@ -36,20 +36,6 @@
 #define MAX_FB_BUFFER	4
 #define DEFAULT_ZPOS	-1
 
-#define _wait_for(COND, MS) ({ \
-	unsigned long timeout__ = jiffies + msecs_to_jiffies(MS);	\
-	int ret__ = 0;							\
-	while (!(COND)) {						\
-		if (time_after(jiffies, timeout__)) {			\
-			ret__ = -ETIMEDOUT;				\
-			break;						\
-		}							\
-	}								\
-	ret__;								\
-})
-
-#define wait_for(COND, MS) _wait_for(COND, MS)
-
 struct drm_device;
 struct exynos_drm_overlay;
 struct drm_connector;
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
index e2abae6..63f0d0f 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
@@ -101,6 +101,8 @@ struct fimd_context {
 	u32				vidcon1;
 	bool				suspended;
 	struct mutex			lock;
+	wait_queue_head_t		wait_vsync_queue;
+	atomic_t			wait_vsync_event;
 
 	struct exynos_drm_panel_info *panel;
 };
@@ -606,11 +608,16 @@ static void fimd_win_disable(struct device *dev, int zpos)
 static void fimd_wait_for_vblank(struct device *dev)
 {
 	struct fimd_context *ctx = get_fimd_context(dev);
-	int ret;
 
-	ret = wait_for((__raw_readl(ctx->regs + VIDCON1) &
-					VIDCON1_VSTATUS_VSYNC), 50);
-	if (ret < 0)
+	atomic_set(&ctx->wait_vsync_event, 1);
+
+	/*
+	 * wait for FIMD to signal VSYNC interrupt or return after
+	 * timeout which is set to 50ms (refresh rate of 20).
+	 */
+	if (!wait_event_timeout(ctx->wait_vsync_queue,
+				!atomic_read(&ctx->wait_vsync_event),
+				DRM_HZ/20))
 		DRM_DEBUG_KMS("vblank wait timed out.\n");
 }
 
@@ -677,6 +684,10 @@ static irqreturn_t fimd_irq_handler(int irq, void *dev_id)
 	drm_handle_vblank(drm_dev, manager->pipe);
 	fimd_finish_pageflip(drm_dev, manager->pipe);
 
+	/* set wait vsync event to zero and wake up queue. */
+	atomic_set(&ctx->wait_vsync_event, 0);
+	DRM_WAKEUP(&ctx->wait_vsync_queue);
+
 out:
 	return IRQ_HANDLED;
 }
@@ -967,6 +978,8 @@ static int __devinit fimd_probe(struct platform_device *pdev)
 	ctx->vidcon1 = pdata->vidcon1;
 	ctx->default_win = pdata->default_win;
 	ctx->panel = panel;
+	DRM_INIT_WAITQUEUE(&ctx->wait_vsync_queue);
+	atomic_set(&ctx->wait_vsync_event, 0);
 
 	subdrv = &ctx->subdrv;
 
diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
index 50100cf..972281e 100644
--- a/drivers/gpu/drm/exynos/exynos_mixer.c
+++ b/drivers/gpu/drm/exynos/exynos_mixer.c
@@ -93,6 +93,8 @@ struct mixer_context {
 	struct hdmi_win_data	win_data[MIXER_WIN_NR];
 	enum mixer_version_id	mxr_ver;
 	void			*parent_ctx;
+	wait_queue_head_t	wait_vsync_queue;
+	atomic_t		wait_vsync_event;
 };
 
 struct mixer_drv_data {
@@ -791,12 +793,16 @@ static void mixer_dpms(void *ctx, int mode)
 static void mixer_wait_for_vblank(void *ctx)
 {
 	struct mixer_context *mixer_ctx = ctx;
-	struct mixer_resources *res = &mixer_ctx->mixer_res;
-	int ret;
 
-	ret = wait_for((mixer_reg_read(res, MXR_INT_STATUS) &
-				MXR_INT_STATUS_VSYNC), 50);
-	if (ret < 0)
+	atomic_set(&mixer_ctx->wait_vsync_event, 1);
+
+	/*
+	 * wait for MIXER to signal VSYNC interrupt or return after
+	 * timeout which is set to 50ms (refresh rate of 20).
+	 */
+	if (!wait_event_timeout(mixer_ctx->wait_vsync_queue,
+				!atomic_read(&mixer_ctx->wait_vsync_event),
+				DRM_HZ/20))
 		DRM_DEBUG_KMS("vblank wait timed out.\n");
 }
 
@@ -957,6 +963,9 @@ static irqreturn_t mixer_irq_handler(int irq, void *arg)
 
 		drm_handle_vblank(drm_hdmi_ctx->drm_dev, ctx->pipe);
 		mixer_finish_pageflip(drm_hdmi_ctx->drm_dev, ctx->pipe);
+
+		atomic_set(&ctx->wait_vsync_event, 0);
+		DRM_WAKEUP(&ctx->wait_vsync_queue);
 	}
 
 out:
@@ -1166,6 +1175,8 @@ static int __devinit mixer_probe(struct platform_device *pdev)
 	drm_hdmi_ctx->ctx = (void *)ctx;
 	ctx->vp_enabled = drv->is_vp_enabled;
 	ctx->mxr_ver = drv->version;
+	DRM_INIT_WAITQUEUE(&ctx->wait_vsync_queue);
+	atomic_set(&ctx->wait_vsync_event, 0);
 
 	platform_set_drvdata(pdev, drm_hdmi_ctx);
 
-- 
1.7.0.4