[Intel-gfx] [PATCH 1/3] drm/i915: Disallow plane x+w>stride on ilk+ with X-tiling

[Ville Syrjälä]

On Tue, Feb 09, 2021 at 09:50:28AM +0000, Chris Wilson wrote:
> Quoting Chris Wilson (2021-02-09 09:22:09)
> > Quoting Ville Syrjala (2021-02-09 02:19:16)
> > > +               while ((src_x + src_w) * cpp > plane_state->color_plane[0].stride) {
> > > +                       if (offset == 0) {
> > > +                               drm_dbg_kms(&dev_priv->drm,
> > > +                                           "Unable to find suitable display surface offset due to X-tiling\n");
> > > +                               return -EINVAL;
> > > +                       }
> > > +
> > > +                       offset = intel_plane_adjust_aligned_offset(&src_x, &src_y, plane_state, 0,
> > > +                                                                  offset, offset - alignment);
> 
> > The reason for choosing a nearby tile offset was to reduce src_x/src_y
> > to fit within the crtc limits. While remapping could be used to solve
> > that, the aligned_offset computation allows reuse of a single view.
> 
> Should there not be a second constraint on the loop to make sure src_x +
> src_w is less than 4095/8191/etc?

Yeah, but we don't have that in the skl code either atm.
Should add it to both.

And if it can actually fail I guess we should just fall back
to remapping rather than telling the user they can't have a
working display. So far I never did the mental gymnastics to
come up with an actually failing scenario.

-- 
Ville Syrjälä
Intel