On Tue, Feb 09, 2016 at 02:29:49PM +0100, Mario Kleiner wrote:
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@gmail.com Cc: stable@vger.kernel.org # 3.18+ Cc: michel@daenzer.net Cc: vbabka@suse.cz Cc: ville.syrjala@linux.intel.com Cc: daniel.vetter@ffwll.ch Cc: dri-devel@lists.freedesktop.org Cc: alexander.deucher@amd.com Cc: christian.koenig@amd.com
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@ffwll.ch
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.
Yeah, just offdelay==0 seems best. Otherwise I think we could actually leave the interrupt enabled indefinitely w/ offdelay>0 since there's not going to be a drm_vblank_put() to arm the disable timer.
-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