The gma500 page-flip code kinda assume that userspace never queues more
then 1 vblank event. So basically it assume that userspace does:
- page-flip
- wait for vblank event
- render
- page-flip
- etc.
In the case where userspace would submit 2 page-flips without waiting
for the first to finish, the current code will just overwrite
gma_crtc->page_flip_event with the event from the 2nd page-flip.
Before this patch if page-flips are submitted then drm_crtc_vblank_get()
will get called twice, where drm_crtc_vblank_put(crtc) will only be run
once, since only 1 event will get reported (the last event set in
gma_crtc->page_flip_event).
Fix the crtc_vblank reference leak by not calling drm_crtc_vblank_get()
when replacing a still set gma_crtc->page_flip_event with a new one.
And while at it add a warning for when userspace tries to queue
multiple page-flips with events attached which gma500 currently
does not support.
Note this is not a real fix for the issue of the gma500 code not
supporting multiple page-flips events being pending, but it at least
improves the situation a bit.
Signed-off-by: Hans de Goede
---
drivers/gpu/drm/gma500/gma_display.c | 11 +++
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/gma500/gma_display.c
b/drivers/gpu/drm/gma500/gma_display.c
index cf038e322164..c4084301afb4 100644
--- a/drivers/gpu/drm/gma500/gma_display.c
+++ b/drivers/gpu/drm/gma500/gma_display.c
@@ -528,10 +528,13 @@ int gma_crtc_page_flip(struct drm_crtc *crtc,
if (event) {
spin_lock_irqsave(>event_lock, flags);
-
- WARN_ON(drm_crtc_vblank_get(crtc) != 0);
-
- gma_crtc->page_flip_event = event;
+ if (!gma_crtc->page_flip_event) {
+ WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+ gma_crtc->page_flip_event = event;
+ } else {
+ drm_warn_once(dev, "page_flip_event already set, gma500
does not support queing multiple events\n");
+ gma_crtc->page_flip_event = event;
+ }
spin_unlock_irqrestore(>event_lock, flags);
/* Call this locked if we want an event at vblank interrupt. */
--
2.36.1
