[Mesa-dev] [PATCH 2/2] i965: Check CCS_E compatibility for texture view rendering

[Jason Ekstrand]

On Fri, Oct 27, 2017 at 3:16 PM, Nanley Chery <nanleychery at gmail.com> wrote:

> On Fri, Oct 27, 2017 at 12:52:30PM -0700, Jason Ekstrand wrote:
> > On Fri, Oct 27, 2017 at 12:24 PM, Nanley Chery <nanleychery at gmail.com>
> > wrote:
> >
> > > Only use CCS_E to render to a texture that is CCS_E-compatible with the
> > > original texture's miptree (linear) format. This prevents render
> > > operations from writing data that can't be decoded with the original
> > > miptree format.
> > >
> > > On Gen10, with the new CCS_E-enabled formats handled, this enables the
> > > driver to pass the arb_texture_view-rendering-formats piglit test.
> > >
> > > Cc: <mesa-stable at lists.freedesktop.org>
> > > Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> > > ---
> > >  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 28
> > > +++++++++++++++++++++++++--
> > >  1 file changed, 26 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > > b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > > index a850f4d17b..59c57c227b 100644
> > > --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > > +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > > @@ -241,6 +241,27 @@ intel_miptree_supports_hiz(const struct
> brw_context
> > > *brw,
> > >     }
> > >  }
> > >
> > > +/**
> > > + * Return true if the format that will be used to access the miptree
> is
> > > + * CCS_E-compatible with the miptree's linear/non-sRGB format.
> > > + *
> > > + * Why use the linear format? Well, although the miptree may be
> specified
> > > with
> > > + * an sRGB format, the usage of that color space/format can be
> toggled.
> > > Since
> > > + * our HW tends to support more linear formats than sRGB ones, we use
> this
> > > + * format variant for check for CCS_E compatibility.
> > > + */
> > > +static bool
> > > +format_ccs_e_compat_with_miptree(const struct gen_device_info
> *devinfo,
> > > +                                 const struct intel_mipmap_tree *mt,
> > > +                                 enum isl_format access_format)
> > > +{
> > > +   assert(mt->aux_usage == ISL_AUX_USAGE_CCS_E);
> > > +
> > > +   mesa_format linear_format = _mesa_get_srgb_format_linear(
> mt->format);
> > > +   enum isl_format isl_format = brw_isl_format_for_mesa_
> > > format(linear_format);
> > > +   return isl_formats_are_ccs_e_compatible(devinfo, isl_format,
> > > access_format);
> > > +}
> > > +
> > >  static bool
> > >  intel_miptree_supports_ccs_e(struct brw_context *brw,
> > >                               const struct intel_mipmap_tree *mt)
> > > @@ -2662,8 +2683,11 @@ intel_miptree_render_aux_usage(struct
> brw_context
> > > *brw,
> > >        return mt->mcs_buf ? ISL_AUX_USAGE_CCS_D : ISL_AUX_USAGE_NONE;
> > >
> > >     case ISL_AUX_USAGE_CCS_E: {
> > > -      /* If the format supports CCS_E, then we can just use it */
> > > -      if (isl_format_supports_ccs_e(&brw->screen->devinfo,
> > > render_format))
> > > +      /* If the format supports CCS_E and is compatible with the
> miptree,
> > > +       * then we can use it.
> > > +       */
> > > +      if (format_ccs_e_compat_with_miptree(&brw->screen->devinfo,
> > > +                                           mt, render_format))
> > >
> >
> > You don't need the helper if you just use mt->surf.format.  That's what
> > can_texture_with_ccs does.
> >
> >
>
> Isn't using mt->surf.format making the code more restrictive than
> necessary? That field may give you the sRGB format of the surface, but
> the helper would always give you the linear variant. Therefore the
> helper allows for CCS_E to be used in more cases.
>

You're right.  I completely missed that.  In that case, we probably want to
use your helper for can_texture_with_ccs as well.  Maybe two patches: one
which adds the helper and makes can_texture_with_ccs use it and a second to
add the render target stuff?  Or you can keep this one as-is and do
can_texture_with_ccs as a follow-on, I don't really care.
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