On 02/09/2016 12:10 PM, Ville Syrjälä wrote:
On Tue, Feb 09, 2016 at 11:06:18AM +0100, Daniel Vetter wrote:
On Mon, Feb 08, 2016 at 02:13:27AM +0100, Mario Kleiner wrote:
drm_vblank_offdelay can have three different types of values:
< 0 is to be always treated the same as dev->vblank_disable_immediate
= 0 is to be treated as "never disable vblanks"
0 is to be treated as disable immediate if kms driver wants it
that way via dev->vblank_disable_immediate. Otherwise it is
a disable timeout in msecs.
This got broken in Linux 3.18+ for the implementation of
drm_vblank_on. If the user specified a value of zero which should
always reenable vblank irqs in this function, a kms driver could
override the users choice by setting vblank_disable_immediate
to true. This patch fixes the regression and keeps the user in
control.
Signed-off-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.18+
Cc: michel@xxxxxxxxxxx
Cc: vbabka@xxxxxxx
Cc: ville.syrjala@xxxxxxxxxxxxxxx
Cc: daniel.vetter@xxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: alexander.deucher@xxxxxxx
Cc: christian.koenig@xxxxxxx
---
drivers/gpu/drm/drm_irq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 5c27ad3..fb17c45 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1492,8 +1492,8 @@ void drm_vblank_on(struct drm_device *dev, unsigned int pipe)
* re-enable interrupts if there are users left, or the
* user wishes vblank interrupts to be enabled all the time.
*/
- if (atomic_read(&vblank->refcount) != 0 ||
- (!dev->vblank_disable_immediate && drm_vblank_offdelay == 0))
+ if (atomic_read(&vblank->refcount) != 0 || drm_vblank_offdelay == 0 ||
+ (!dev->vblank_disable_immediate && drm_vblank_offdelay > 0))
Hm, shouldn't we change this to only enable the vblank irq if we need it,
i.e. offdelay == 0? For delayed disabling there's kinda no need to enable
it superflously after a modeset, if userspace didn't yet ask for vblank
timestamps. But then is was specifically added by Ville in cd19e52aee922,
so I guess someone really wants this.
IIRC what I wanted was to just re-enable the interrupt for the offdelay==0
case. I think it just ended up as a mess due to changing some of the
semantics of offdelay<0 vs. offdelay==0 vs. disable_immediate during the
review of the series. So yeah, given how drm_vblank_put() works now, I'd
just make this check for offdelay==0.
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
I can change that to offdelay==0 only, if you want. It was mostly about
preserving what's there while at the same time fixing the important
offdelay==0 user override.
-mario
WARN_ON(drm_vblank_enable(dev, pipe));
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
}
--
1.9.1
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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