On Fri, Nov 13, 2015 at 11:20:19PM +0200, Ville Syrjälä wrote:
> On Fri, Nov 13, 2015 at 09:03:43PM +0000, Chris Wilson wrote:
> > On Fri, Nov 13, 2015 at 05:53:41PM -0200, Paulo Zanoni wrote:
> > > Instead of waiting for 50ms, just wait until the next vblank, since
> > > it's the minimum requirement.
> > >
> > > This moves PC7 residency on my specific BDW machine running Cinnamon
> > > from 60-70% to 84-89%. Without FBC, I get 20-25%. I'm using a
> > > 3200x1800 eDP panel. Notice: this was the case when the patch was
> > > originally proposed, the order of the FBC patches changed since then,
> > > so the actual numbers might be slightly different now.
> > >
> > > v2:
> > > - Rebase after changing the patch order.
> > > - Update the commit message.
> > >
> > > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/i915/i915_drv.h | 2 +-
> > > drivers/gpu/drm/i915/intel_fbc.c | 12 +++---------
> > > 2 files changed, 4 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > > index 9418bd5..ea08714 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > @@ -919,9 +919,9 @@ struct i915_fbc {
> > >
> > > struct intel_fbc_work {
> > > bool scheduled;
> > > + u32 scheduled_vblank;
> > > struct work_struct work;
> > > struct drm_framebuffer *fb;
> > > - unsigned long enable_jiffies;
> > > } work;
> > >
> > > const char *no_fbc_reason;
> > > diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> > > index aa82075..72de8a1 100644
> > > --- a/drivers/gpu/drm/i915/intel_fbc.c
> > > +++ b/drivers/gpu/drm/i915/intel_fbc.c
> > > @@ -391,7 +391,6 @@ static void intel_fbc_work_fn(struct work_struct *__work)
> > > container_of(__work, struct drm_i915_private, fbc.work.work);
> > > struct intel_fbc_work *work = &dev_priv->fbc.work;
> > > struct intel_crtc *crtc = dev_priv->fbc.crtc;
> > > - unsigned long delay_jiffies = msecs_to_jiffies(50);
> > >
> > > retry:
> > > /* Delay the actual enabling to let pageflipping cease and the
> > > @@ -400,14 +399,9 @@ retry:
> > > * vblank to pass after disabling the FBC before we attempt
> > > * to modify the control registers.
> > > *
> > > - * A more complicated solution would involve tracking vblanks
> > > - * following the termination of the page-flipping sequence
> > > - * and indeed performing the enable as a co-routine and not
> > > - * waiting synchronously upon the vblank.
> > > - *
> > > * WaFbcWaitForVBlankBeforeEnable:ilk,snb
> > > */
> > > - wait_remaining_ms_from_jiffies(work->enable_jiffies, delay_jiffies);
> > > + intel_wait_for_vblank(dev_priv->dev, crtc->pipe);
> > >
> > > mutex_lock(&dev_priv->fbc.lock);
> > >
> > > @@ -416,7 +410,7 @@ retry:
> > > goto out;
> > >
> > > /* Were we delayed again while this function was sleeping? */
> > > - if (time_after(work->enable_jiffies + delay_jiffies, jiffies)) {
> > > + if (drm_crtc_vblank_get(&crtc->base) == work->scheduled_vblank) {
> > > mutex_unlock(&dev_priv->fbc.lock);
> > > goto retry;
> > > }
> > > @@ -449,7 +443,7 @@ static void intel_fbc_schedule_activation(struct intel_crtc *crtc)
> > > * jiffy count. */
> > > work->fb = crtc->base.primary->fb;
> > > work->scheduled = true;
> > > - work->enable_jiffies = jiffies;
> > > + work->scheduled_vblank = drm_crtc_vblank_count(&crtc->base);
> >
> > Isn't the frame counter only incrementing whilst the vblank IRQ is
> > enabled? Ville?
>
> I see a "+ if (drm_crtc_vblank_get(" earlier.
Hmm. Actually it's doing
"drm_crtc_vblank_get(&crtc->base) == work->scheduled_vblank)"
which looks rather like nonsense.
Not sure what the intention here was...
--
Ville Syrjälä
Intel OTC
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