The pipe might already have been shut down, and then it's not a good
idea to call hw accessor functions. Instead use the same logic as
drm_vblank_off which has all the necessary checks to avoid troubles or
inconsistency.
Noticed by Imre while reviewing my patches to remove some sanity
checks from ->get_vblank_counter.
v2: Try harder. disable_and_save can still access the vblank stuff
when vblank->enabled isn't set. It has to, since vlbank irq could be
disable but the pipe is still on when being called from
drm_vblank_off. But we still want to use that code for more code
sharing. So add a check for vblank->enabled on top - if that's not set
we shouldn't have anyone waiting for the vblank. If we have that's a
pretty serious bug.
The other issue that Imre spotted is drm_vblank_cleanup. That code
again calls disable_and_save and so suffers from the same issues. But
really drm_irq_uninstall should have cleaned that all up, so replace
the code with WARN_ON. Note that we can't delete the timer cleanup
since drivers aren't required to use drm_irq_install/uninstall, but
can do their own irq handling.
v3: Make it clear that all that gunk in drm_irq_uninstall is really
just bandaids for UMS races between the irq/vblank code. In UMS
userspace is in control of enabling/disabling interrupts in general
and vblanks specifically.
v4: Imre observed that KMS drivers all call drm_vblank_cleanup before
drm_irq_uninstall (as they should), so again the code in there is dead
for KMS (due to dev->num_crtcs == 0 after drm_vblank_cleanup). Or
should be, so only WARN for KMS - with UMS userspace could try to do
evil things.
v5: After more discussion on irc we've gone back to v3: the
del_timer_sync is required in all cases in drm_vblank_cleanup, but
let's restrict the WARN_ON to kms drivers only. Imre was also
concerned that bad things could happen without the disable_and_save
call. But we immediately free vblank structures afterwards which makes
the save useless. And drm_handle_vblank has a check for dev->num_crtcs
to avoid surprises with ums.
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
drivers/gpu/drm/drm_irq.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 1e5fb1b994d7..3c18e522cc3b 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -269,7 +269,6 @@ static void vblank_disable_fn(unsigned long arg)
void drm_vblank_cleanup(struct drm_device *dev)
{
int crtc;
- unsigned long irqflags;
/* Bail if the driver didn't call drm_vblank_init() */
if (dev->num_crtcs == 0)
@@ -278,11 +277,10 @@ void drm_vblank_cleanup(struct drm_device *dev)
for (crtc = 0; crtc < dev->num_crtcs; crtc++) {
struct drm_vblank_crtc *vblank = &dev->vblank[crtc];
- del_timer_sync(&vblank->disable_timer);
+ WARN_ON(vblank->enabled &&
+ drm_core_check_feature(dev, DRIVER_MODESET));
- spin_lock_irqsave(&dev->vbl_lock, irqflags);
- vblank_disable_and_save(dev, crtc);
- spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+ del_timer_sync(&vblank->disable_timer);
}
kfree(dev->vblank);
@@ -468,17 +466,23 @@ int drm_irq_uninstall(struct drm_device *dev)
dev->irq_enabled = false;
/*
- * Wake up any waiters so they don't hang.
+ * Wake up any waiters so they don't hang. This is just to paper over
+ * isssues for UMS drivers which aren't in full control of their
+ * vblank/irq handling. KMS drivers must ensure that vblanks are all
+ * disabled when uninstalling the irq handler.
*/
if (dev->num_crtcs) {
spin_lock_irqsave(&dev->vbl_lock, irqflags);
for (i = 0; i < dev->num_crtcs; i++) {
struct drm_vblank_crtc *vblank = &dev->vblank[i];
+ if (!vblank->enabled)
+ continue;
+
+ WARN_ON(drm_core_check_feature(dev, DRIVER_MODESET));
+
+ vblank_disable_and_save(dev, i);
wake_up(&vblank->queue);
- vblank->enabled = false;
- vblank->last =
- dev->driver->get_vblank_counter(dev, i);
}
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
}
--
1.9.3
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