drm/exynos: track vblank events on a per crtc basis

The goal of the change is to make sure we send the vblank event on the
current vblank. My hope is to fix any races that might be causing flicker.
After this change I only see a flicker in the transition plymouth and
X11.

Simplified the code by tracking vblank events on a per-crtc basis. This
allowed me to remove all error paths from the callback. It also allowed
me to remove the vblank wait from the callback.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

1 files changed, 42 insertions, 50 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
index 47dd2b0f4aa5..eb49195cec5c 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
@@ -34,9 +34,8 @@ static void exynos_drm_crtc_dpms(struct drm_crtc *crtc, int mode)
 	if (mode > DRM_MODE_DPMS_ON) {
 		/* wait for the completion of page flip. */
 		if (!wait_event_timeout(exynos_crtc->pending_flip_queue,
-				!atomic_read(&exynos_crtc->pending_flip),
-				HZ/20))
-			atomic_set(&exynos_crtc->pending_flip, 0);
+				(exynos_crtc->event == NULL), HZ/20))
+			exynos_crtc->event = NULL;
 		drm_crtc_vblank_off(crtc);
 	}
 
@@ -164,11 +163,10 @@ static int exynos_drm_crtc_page_flip(struct drm_crtc *crtc,
 				     uint32_t page_flip_flags)
 {
 	struct drm_device *dev = crtc->dev;
-	struct exynos_drm_private *dev_priv = dev->dev_private;
 	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(crtc);
 	struct drm_framebuffer *old_fb = crtc->primary->fb;
 	unsigned int crtc_w, crtc_h;
-	int ret = -EINVAL;
+	int ret;
 
 	/* when the page flip is requested, crtc's dpms should be on */
 	if (exynos_crtc->dpms > DRM_MODE_DPMS_ON) {
@@ -176,48 +174,49 @@ static int exynos_drm_crtc_page_flip(struct drm_crtc *crtc,
 		return -EINVAL;
 	}
 
-	mutex_lock(&dev->struct_mutex);
+	if (!event)
+		return -EINVAL;
 
-	if (event) {
-		/*
-		 * the pipe from user always is 0 so we can set pipe number
-		 * of current owner to event.
-		 */
-		event->pipe = exynos_crtc->pipe;
+	spin_lock_irq(&dev->event_lock);
+	if (exynos_crtc->event) {
+		ret = -EBUSY;
+		goto out;
+	}
 
-		ret = drm_vblank_get(dev, exynos_crtc->pipe);
-		if (ret) {
-			DRM_DEBUG("failed to acquire vblank counter\n");
+	ret = drm_vblank_get(dev, exynos_crtc->pipe);
+	if (ret) {
+		DRM_DEBUG("failed to acquire vblank counter\n");
+		goto out;
+	}
 
-			goto out;
-		}
+	exynos_crtc->event = event;
+	spin_unlock_irq(&dev->event_lock);
 
+	/*
+	 * the pipe from user always is 0 so we can set pipe number
+	 * of current owner to event.
+	 */
+	event->pipe = exynos_crtc->pipe;
+
+	crtc->primary->fb = fb;
+	crtc_w = fb->width - crtc->x;
+	crtc_h = fb->height - crtc->y;
+	ret = exynos_update_plane(crtc->primary, crtc, fb, 0, 0,
+				  crtc_w, crtc_h, crtc->x, crtc->y,
+				  crtc_w, crtc_h);
+	if (ret) {
+		crtc->primary->fb = old_fb;
 		spin_lock_irq(&dev->event_lock);
-		list_add_tail(&event->base.link,
-				&dev_priv->pageflip_event_list);
-		atomic_set(&exynos_crtc->pending_flip, 1);
+		exynos_crtc->event = NULL;
+		drm_vblank_put(dev, exynos_crtc->pipe);
 		spin_unlock_irq(&dev->event_lock);
-
-		crtc->primary->fb = fb;
-		crtc_w = fb->width - crtc->x;
-		crtc_h = fb->height - crtc->y;
-		ret = exynos_update_plane(crtc->primary, crtc, fb, 0, 0,
-					  crtc_w, crtc_h, crtc->x, crtc->y,
-					  crtc_w, crtc_h);
-		if (ret) {
-			crtc->primary->fb = old_fb;
-
-			spin_lock_irq(&dev->event_lock);
-			drm_vblank_put(dev, exynos_crtc->pipe);
-			list_del(&event->base.link);
-			atomic_set(&exynos_crtc->pending_flip, 0);
-			spin_unlock_irq(&dev->event_lock);
-
-			goto out;
-		}
+		return ret;
 	}
+
+	return 0;
+
 out:
-	mutex_unlock(&dev->struct_mutex);
+	spin_unlock_irq(&dev->event_lock);
 	return ret;
 }
 
@@ -255,7 +254,6 @@ struct exynos_drm_crtc *exynos_drm_crtc_create(struct drm_device *drm_dev,
 		return ERR_PTR(-ENOMEM);
 
 	init_waitqueue_head(&exynos_crtc->pending_flip_queue);
-	atomic_set(&exynos_crtc->pending_flip, 0);
 
 	exynos_crtc->dpms = DRM_MODE_DPMS_OFF;
 	exynos_crtc->pipe = pipe;
@@ -313,26 +311,20 @@ void exynos_drm_crtc_disable_vblank(struct drm_device *dev, int pipe)
 void exynos_drm_crtc_finish_pageflip(struct drm_device *dev, int pipe)
 {
 	struct exynos_drm_private *dev_priv = dev->dev_private;
-	struct drm_pending_vblank_event *e, *t;
 	struct drm_crtc *drm_crtc = dev_priv->crtc[pipe];
 	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(drm_crtc);
 	unsigned long flags;
 
 	spin_lock_irqsave(&dev->event_lock, flags);
+	if (exynos_crtc->event) {
 
-	list_for_each_entry_safe(e, t, &dev_priv->pageflip_event_list,
-			base.link) {
-		/* if event's pipe isn't same as crtc then ignore it. */
-		if (pipe != e->pipe)
-			continue;
-
-		list_del(&e->base.link);
-		drm_send_vblank_event(dev, -1, e);
+		drm_send_vblank_event(dev, -1, exynos_crtc->event);
 		drm_vblank_put(dev, pipe);
-		atomic_set(&exynos_crtc->pending_flip, 0);
 		wake_up(&exynos_crtc->pending_flip_queue);
+
 	}
 
+	exynos_crtc->event = NULL;
 	spin_unlock_irqrestore(&dev->event_lock, flags);
 }