drm-vblank: Always return true vblank count of scheduled vblank event.
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@tuebingen.mpg.de> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org> Signed-off-by: Dave Airlie <airlied@redhat.com>
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@ -1086,15 +1086,18 @@ static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
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e->event.sequence = vblwait->request.sequence;
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if ((seq - vblwait->request.sequence) <= (1 << 23)) {
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e->event.sequence = seq;
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e->event.tv_sec = now.tv_sec;
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e->event.tv_usec = now.tv_usec;
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drm_vblank_put(dev, e->pipe);
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list_add_tail(&e->base.link, &e->base.file_priv->event_list);
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wake_up_interruptible(&e->base.file_priv->event_wait);
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vblwait->reply.sequence = seq;
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trace_drm_vblank_event_delivered(current->pid, pipe,
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vblwait->request.sequence);
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} else {
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list_add_tail(&e->base.link, &dev->vblank_event_list);
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vblwait->reply.sequence = vblwait->request.sequence;
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}
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spin_unlock_irqrestore(&dev->event_lock, flags);
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