[Intel-gfx] [PATCH 3/4] drm/i915: don't disable FBC for pipe A when flipping pipe B

[Rodrigo Vivi]

On Wed, Jul 15, 2015 at 5:31 AM Daniel Vetter <daniel at ffwll.ch> wrote:

> On Tue, Jul 14, 2015 at 04:29:13PM -0300, Paulo Zanoni wrote:
> > From: Paulo Zanoni <paulo.r.zanoni at intel.com>
> >
> > Use the appropriate call.
>

Good!

Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>


> >
> > I know there's a discussion about whether we need this call here at
> > all, but removing the call means we'll only update FBC after we get
> > the page flip IRQ. So the user may only see the new frame a little
> > after it should. Let's wait just a little bit more before removing
> > this call since we can rely in the HW tracking for accurate flips.
>

I'm in favor of remove or at least move to frontbuffer prepare for flip..


>
> Afaik fbc2 on g4x+ does correctly invalidate the fbc cache when flipping
> the frontbuffer. This was needed for fbc1 which just didn't handle flips -
> there we had to essentially disable and then re-enable fbc to make sure
> the update was tracked correctly.
>
> The other problem is correctly synchronizing the fence update (for hw gtt
> tracking) against the flip. I'm not sure whether we still have races left
> there, but simply updating the fence window before we flip should be all
> that's required.


But anyway I'm also in favor of removing the old fbc...


> -Daniel
>
> >
> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> > index 37b2528..6e3ba5f 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -11544,7 +11544,7 @@ static int intel_crtc_page_flip(struct drm_crtc
> *crtc,
> >                         to_intel_plane(primary)->frontbuffer_bit);
> >       mutex_unlock(&dev->struct_mutex);
> >
> > -     intel_fbc_disable(dev_priv);
> > +     intel_fbc_disable_crtc(intel_crtc);
> >       intel_frontbuffer_flip_prepare(dev,
> >
> to_intel_plane(primary)->frontbuffer_bit);
> >
> > --
> > 2.1.4
> >
> > _______________________________________________
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> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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>
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