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@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. 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 > > -- Ville Syrjälä Intel OTC -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html