On Tue, May 26, 2015 at 01:48:11PM +0200, Daniel Vetter wrote:
> On Tue, May 26, 2015 at 05:53:38PM +0900, Michel Dänzer wrote:
> > From: Michel Dänzer <michel.daenzer@xxxxxxx>
> >
> > dev->max_vblank_count contains the largest value that can be represented
> > by the hardware counter. When the hardware counter wraps around, we have
> > to add that value + 1 to get the same value as if the hardware counter
> > didn't wrap around.
> >
> > Signed-off-by: Michel Dänzer <michel.daenzer@xxxxxxx>
>
> Well there's two users of this really, one wants the max (this one here)
> and the other a mask. And all the drivers use it as a mask. Maybe rename
> it to vblank_counter_mask or similar while at it to prevent further
> confusion?
Well, really it's just 'value % (max + 1)'. Just happens to work with &
since it's POT-1.
> -Daniel
>
> > ---
> > 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 c8a3447..f9634da 100644
> > --- a/drivers/gpu/drm/drm_irq.c
> > +++ b/drivers/gpu/drm/drm_irq.c
> > @@ -100,7 +100,7 @@ static void drm_update_vblank_count(struct drm_device *dev, int crtc)
> > /*
> > * Interrupts were disabled prior to this call, so deal with counter
> > * wrap if needed.
> > - * NOTE! It's possible we lost a full dev->max_vblank_count events
> > + * NOTE! It's possible we lost a full dev->max_vblank_count + 1 events
> > * here if the register is small or we had vblank interrupts off for
> > * a long time.
> > *
> > @@ -117,7 +117,7 @@ static void drm_update_vblank_count(struct drm_device *dev, int crtc)
> > /* Deal with counter wrap */
> > diff = cur_vblank - vblank->last;
> > if (cur_vblank < vblank->last) {
> > - diff += dev->max_vblank_count;
> > + diff += dev->max_vblank_count + 1;
> >
> > DRM_DEBUG("last_vblank[%d]=0x%x, cur_vblank=0x%x => diff=0x%x\n",
> > crtc, vblank->last, cur_vblank, diff);
> > --
> > 2.1.4
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
> _______________________________________________
> dri-devel mailing list
> dri-devel@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Ville Syrjälä
Intel OTC
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/dri-devel
