Em Sex, 2015-11-13 às 21:03 +0000, Chris Wilson escreveu:
> 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?
At the work function we call intel_wait_for_vblank(), which calls
drm_wait_one_vblank(), which calls drm_vblank_get().
> -Chris
>
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