On Wed, Jan 29, 2020 at 01:44:49PM +0200, Ville Syrjälä wrote:
> On Tue, Jan 28, 2020 at 03:52:40PM -0800, José Roberto de Souza wrote:
> > dGFX have local memory so it do not have aperture and do not support
> > CPU fences but even for iGFX it have a small number of fences.
> >
> > As replacement for fences to track frontbuffer modifications by CPU
> > we have a software tracking that is already in used by FBC and PSR.
> > PSR don't support fences so it shows that this tracking is reliable.
> >
> > So lets make fences a nice-to-have to activate FBC for GEN9+(as we
> > only have a good CI coverage for GEN9+), this will allow us to enable
> > FBC for dGFXs and iGFXs even when there is no available fence.
> >
> > intel_fbc_hw_tracking_covers_screen() maybe can also have the same
> > treatment as fences but BSpec is not clear if the size limitation is
> > for hardware tracking or general use of FBC and I don't have a 5K
> > display to test it, so keeping as is for safety.
> >
> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> > Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/display/intel_fbc.c | 12 ++++++++----
> > 1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> > index 2a3f1333c8ff..1f0d24a1dec1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> > @@ -717,11 +717,15 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
> > return false;
> > }
> >
> > - /* The use of a CPU fence is mandatory in order to detect writes
> > - * by the CPU to the scanout and trigger updates to the FBC.
> > + /* The use of a CPU fence is one of two ways to detect writes by the
> > + * CPU to the scanout and trigger updates to the FBC.
> > + *
> > + * The other method is by software tracking(see
> > + * intel_fbc_invalidate/flush()), it will manually notify FBC and nuke
> > + * the current compressed buffer and recompress it.
> > *
> > * Note that is possible for a tiled surface to be unmappable (and
> > - * so have no fence associated with it) due to aperture constaints
> > + * so have no fence associated with it) due to aperture constraints
> > * at the time of pinning.
> > *
> > * FIXME with 90/270 degree rotation we should use the fence on
> > @@ -730,7 +734,7 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
> > * For now this will effecively disable FBC with 90/270 degree
> > * rotation.
> > */
> > - if (cache->fence_id < 0) {
> > + if (cache->fence_id < 0 && INTEL_GEN(dev_priv) < 9) {
>
> Not enough. We need to check that the tiling format is actually supported.
Actually not sure if all of them are or not. IIRC some docs just said
X/Y tile is supported (and in some other place linear was also listed).
> Also the tracking stuff is busted in intel ddx so need to get
> https://patchwork.freedesktop.org/series/70636/ merged somehow.
>
> > fbc->no_fbc_reason = "framebuffer not tiled or fenced";
> > return false;
> > }
> > --
> > 2.25.0
> >
> > _______________________________________________
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> > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Ville Syrjälä
> Intel
--
Ville Syrjälä
Intel
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