On Tue, Mar 04, 2014 at 10:16:02AM +0100, Daniel Vetter wrote:
> On Fri, Feb 21, 2014 at 09:03:34PM +0200, ville.syrjala@xxxxxxxxxxxxxxx wrote:
> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >
> > If someone holds a vblank reference across the modeset, and after/during
> > the modeset someone tries to grab a vblank reference, the current code
> > won't re-enable the vblank interrupts. That's not good, so instead allow
> > the driver to choose whether drm_vblank_get() should always enable the
> > interrupts regardless of the refcount.
> >
> > Combined with the drm_vblank_off/drm_vblank_on reject mechanism, this
> > can also be used to allow drivers to use vblank interrupts during
> > modeset, whether or not someone is currently holding a vblank reference.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/drm_irq.c | 3 ++-
> > include/drm/drmP.h | 6 ++++++
> > 2 files changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> > index 6e5d820..d613b6f 100644
> > --- a/drivers/gpu/drm/drm_irq.c
> > +++ b/drivers/gpu/drm/drm_irq.c
> > @@ -897,7 +897,8 @@ int drm_vblank_get(struct drm_device *dev, int crtc)
> > }
> >
> > /* Going from 0->1 means we have to enable interrupts again */
> > - if (atomic_add_return(1, &dev->vblank[crtc].refcount) == 1) {
> > + if (atomic_add_return(1, &dev->vblank[crtc].refcount) == 1 ||
> > + dev->vblank_always_enable_on_get) {
> > spin_lock(&dev->vblank_time_lock);
> > if (!dev->vblank[crtc].enabled) {
> > /* Enable vblank irqs under vblank_time_lock protection.
> > diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> > index ee40483..3eca0ee 100644
> > --- a/include/drm/drmP.h
> > +++ b/include/drm/drmP.h
> > @@ -1156,6 +1156,12 @@ struct drm_device {
> > */
> > bool vblank_disable_allowed;
> >
> > + /*
> > + * Should a non-rejected drm_vblank_get() always enable the
> > + * vblank interrupt regardless of the current refcount?
> > + */
> > + bool vblank_always_enable_on_get;
>
> Nack for this hack. Why can't drm_vblank_on not just re-enable the vblank
> interrupt if we still have a vblank reference?
Hmm. Yeah that seems like a nicer way to go about it.
--
Ville Syrjälä
Intel OTC
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