On Fri, May 01, 2020 at 05:16:13PM -0700, Matt Roper wrote:
> On Wed, Apr 29, 2020 at 06:29:21PM +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrj...@linux.intel.com>
> > 
> > Consult the actual plane stride instead of the fb stride. The two
> > will disagree when we remap the gtt. The plane stride is what the
> > hw will be fed so that's what we should look at for the FBC
> > retrictions/cfb allocation.
> > 
> > Since we no longer require a fence we are going to attempt using
> > FBC with remapping, and so we should look at correct stride.
> > 
> > With 90/270 degree rotation the plane stride is stored in units
> > of pixels, so we need to conver it to bytes for the purposes
> > of calculating the cfb stride. Not entirely sure if this matches
> > the hw behaviour though. Need to reverse engineer that at some
> > point...
> > 
> > We also need to reorder the pixel format check vs. stride check
> > to avoid triggering a spurious WARN(stride & 63) with cpp==1 and
> > plane stride==32.
> > 
> > v2: Try to deal with rotated stride and related WARN
> > 
> > Cc: José Roberto de Souza <jose.so...@intel.com>
> > Fixes: 691f7ba58d52 ("drm/i915/display/fbc: Make fences a nice-to-have for 
> > GEN9+")
> > Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_fbc.c | 16 ++++++++++------
> >  1 file changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c 
> > b/drivers/gpu/drm/i915/display/intel_fbc.c
> > index 7194f9bc62c5..7f2b2382b813 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> > @@ -707,9 +707,13 @@ static void intel_fbc_update_state_cache(struct 
> > intel_crtc *crtc,
> >     cache->plane.pixel_blend_mode = plane_state->hw.pixel_blend_mode;
> >  
> >     cache->fb.format = fb->format;
> > -   cache->fb.stride = fb->pitches[0];
> >     cache->fb.modifier = fb->modifier;
> >  
> > +   /* FIXME is this correct? */
> > +   cache->fb.stride = plane_state->color_plane[0].stride;
> 
> We still have a comment in intel_fbc_calculate_cfb_size() that indicates
> that we need to use the framebuffer stride instead of the plane stride
> (explicitly added in commit 850bfaab7120a).

That's not really what it's saying. full buffer stride == plane stride,
vs. active area == plane width

> The bspec (page 49227) uses
> terminology "Stride of plane uncompressed surface" which sounds like
> framebuffer size to me; I'm not sure if switching it to the plane's size
> will cause problems if the plane is only scanning out a subregion of the
> framebuffer?

There is no framebuffer stride as far as the hardware is concerned.
There is only plane width and plane stride.

> 
> If it really is safe to use the plane size instead of the framebuffer
> size, then I think we at least need to remove or change that comment
> too.
> 
> 
> Matt
> 
> > +   if (drm_rotation_90_or_270(plane_state->hw.rotation))
> > +           cache->fb.stride *= fb->format->cpp[0];
> > +
> >     drm_WARN_ON(&dev_priv->drm, plane_state->flags & PLANE_HAS_FENCE &&
> >                 !plane_state->vma->fence);
> >  
> > @@ -804,6 +808,11 @@ static bool intel_fbc_can_activate(struct intel_crtc 
> > *crtc)
> >             return false;
> >     }
> >  
> > +   if (!pixel_format_is_valid(dev_priv, cache->fb.format->format)) {
> > +           fbc->no_fbc_reason = "pixel format is invalid";
> > +           return false;
> > +   }
> > +
> >     if (!rotation_is_valid(dev_priv, cache->fb.format->format,
> >                            cache->plane.rotation)) {
> >             fbc->no_fbc_reason = "rotation unsupported";
> > @@ -820,11 +829,6 @@ static bool intel_fbc_can_activate(struct intel_crtc 
> > *crtc)
> >             return false;
> >     }
> >  
> > -   if (!pixel_format_is_valid(dev_priv, cache->fb.format->format)) {
> > -           fbc->no_fbc_reason = "pixel format is invalid";
> > -           return false;
> > -   }
> > -
> >     if (cache->plane.pixel_blend_mode != DRM_MODE_BLEND_PIXEL_NONE &&
> >         cache->fb.format->has_alpha) {
> >             fbc->no_fbc_reason = "per-pixel alpha blending is incompatible 
> > with FBC";
> > -- 
> > 2.24.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Matt Roper
> Graphics Software Engineer
> VTT-OSGC Platform Enablement
> Intel Corporation
> (916) 356-2795

-- 
Ville Syrjälä
Intel
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