-------- Original Message --------
Subject: [PATCH] drm-vblank: Always return true vblank count of
scheduled vblank event.
Date: Fri, 10 Dec 2010 15:58:10 +0100
From: Mario Kleiner <mario.klei...@tuebingen.mpg.de>
To: airlied at gmail.com
CC: jbarnes at virtuousgeek.org, krh at bitplanet.net, Mario Kleiner
<mario.kleiner at tuebingen.mpg.de>
This patch tries to make sure that the vbl.reply.sequence
vblank count for a queued or emitted vblank event always
corresponds to the true vblank count of queueing/emission, so
the ddx can rely on the returned target_msc for consistency
checks and implementation of swap_intervals in glXSwapBuffers().
Without this there is a small race-condition between the
userspace ddx queueing a vblank event and the vblank
counter incrementing before the event gets queued in
the kernel.
Signed-off-by: Mario Kleiner <mario.kleiner at tuebingen.mpg.de>
---
drivers/gpu/drm/drm_irq.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 4e82d0d..55160d7 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1086,15 +1086,18 @@ static int drm_queue_vblank_event(struct
drm_device *dev, int pipe,
e->event.sequence = vblwait->request.sequence;
if ((seq - vblwait->request.sequence) <= (1 << 23)) {
+ e->event.sequence = seq;
e->event.tv_sec = now.tv_sec;
e->event.tv_usec = now.tv_usec;
drm_vblank_put(dev, e->pipe);
list_add_tail(&e->base.link, &e->base.file_priv->event_list);
wake_up_interruptible(&e->base.file_priv->event_wait);
+ vblwait->reply.sequence = seq;
trace_drm_vblank_event_delivered(current->pid, pipe,
vblwait->request.sequence);
} else {
list_add_tail(&e->base.link, &dev->vblank_event_list);
+ vblwait->reply.sequence = vblwait->request.sequence;
}
spin_unlock_irqrestore(&dev->event_lock, flags);
--
1.7.0.4
