[Mesa-dev] [PATCH 2/2] i965/cnl: Correctly sample from fast-cleared sRGB textures

Jason Ekstrand jason at jlekstrand.net
Mon Nov 20 22:55:28 UTC 2017


On Mon, Nov 20, 2017 at 2:10 PM, Nanley Chery <nanleychery at gmail.com> wrote:

> On Mon, Nov 20, 2017 at 01:54:39PM -0800, Nanley Chery wrote:
> > When sampling from fast-cleared sRGB textures on gen10, the hardware
> > will not decode the clear color to linear. We must therefore do it in
> > software.
> >
>
> I should've included the tests that are now passing (added in locally):
>
> * spec at arb_framebuffer_srgb@arb_framebuffer_srgb-fast-clear-blend
> * spec at arb_framebuffer_srgb@fbo-fast-clear
> * spec at arb_framebuffer_srgb@msaa-fast-clear
> * spec at ext_texture_srgb@fbo-fast-clear
> * spec at ext_texture_srgb@multisample-fast-clear gl_ext_texture_srgb
>
> -Nanley
>
> > Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> > ---
> >  src/mesa/drivers/dri/i965/brw_blorp.c            |  7 +++++
> >  src/mesa/drivers/dri/i965/brw_meta_util.c        | 38
> ++++++++++++++++++++++++
> >  src/mesa/drivers/dri/i965/brw_meta_util.h        |  5 ++++
> >  src/mesa/drivers/dri/i965/brw_wm_surface_state.c |  9 +++++-
> >  4 files changed, 58 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_blorp.c
> b/src/mesa/drivers/dri/i965/brw_blorp.c
> > index 38284d3b85..b10e9b95b7 100644
> > --- a/src/mesa/drivers/dri/i965/brw_blorp.c
> > +++ b/src/mesa/drivers/dri/i965/brw_blorp.c
> > @@ -328,6 +328,13 @@ brw_blorp_blit_miptrees(struct brw_context *brw,
> >     struct blorp_surf src_surf, dst_surf;
> >     blorp_surf_for_miptree(brw, &src_surf, src_mt, src_aux_usage, false,
> >                            &src_level, src_layer, 1, &tmp_surfs[0]);
> > +   if (devinfo->gen >= 10 && isl_format_is_srgb(src_isl_format) &&
> > +       src_clear_supported) {
> > +      src_surf.clear_color =
> > +         gen10_convert_srgb_fast_clear_color(devinfo, src_isl_format,
> > +                                             src_mt->fast_clear_color);
> > +   }
> > +
> >     blorp_surf_for_miptree(brw, &dst_surf, dst_mt, dst_aux_usage, true,
> >                            &dst_level, dst_layer, 1, &tmp_surfs[1]);
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_meta_util.c
> b/src/mesa/drivers/dri/i965/brw_meta_util.c
> > index d292f5a8e2..97c6114f8a 100644
> > --- a/src/mesa/drivers/dri/i965/brw_meta_util.c
> > +++ b/src/mesa/drivers/dri/i965/brw_meta_util.c
> > @@ -28,6 +28,7 @@
> >  #include "brw_state.h"
> >  #include "main/blend.h"
> >  #include "main/fbobject.h"
> > +#include "main/format_utils.h"
> >  #include "util/format_srgb.h"
> >
> >  /**
> > @@ -315,6 +316,43 @@ brw_is_color_fast_clear_compatible(struct
> brw_context *brw,
> >     return true;
> >  }
> >
> > +/* When sampling from fast-cleared sRGB textures on gen10, the hardware
> > + * will not decode the clear color to linear. We must therefore do it in
> > + * software.
> > + */
> > +union isl_color_value
> > +gen10_convert_srgb_fast_clear_color(const struct gen_device_info
> *devinfo,
> > +                                    enum isl_format format,
> > +                                    const union isl_color_value color)
> > +{
> > +   assert(devinfo->gen >= 10);
> > +   assert(isl_format_is_srgb(format));
> > +   assert(isl_format_supports_ccs_d(devinfo, format));
> > +
> > +   /* All the CCS-supported sRGB textures in GL are 4-channel,
> 8-bit/channel,
> > +    * UNORM formats.
> > +    */
> > +   assert(isl_format_get_num_channels(format) == 4);
> > +   assert(isl_format_channels_have_size(format, 8));
> > +   assert(isl_format_has_unorm_channel(format));
>

There are exactly 4 ISL formats which match this.  You could just assert
that it's one of the four and drop the other 5 asserts.  It doesn't really
matter, but this is rather complicated.


> > +
> > +   /* According to do_single_blorp_clear(), fast-clears for
> texture-views are
> > +    * disabled. This means that we only have to do channel-to-channel
> format
> > +    * conversions.
> > +    */
> > +   union isl_color_value override_color = color;
> > +   for (unsigned i = 0; i < 3; i++) {
> > +      /* According to brw_is_color_fast_clear_compatible(), only
> floating-point
> > +       * fast-clears have been enabled, so it is safe to rely on
> > +       * isl_color_value::f32.
> > +       */
>

There is no such thing as integer sRGB, it wouldn't even make sense.


> > +      const uint8_t srgb_unorm8 = _mesa_float_to_unorm(color.f32[i],
> 8);
> > +      override_color.f32[i] =
> > +         util_format_srgb_8unorm_to_linear_float(srgb_unorm8);
>

Any particular reason why you're going through 8-bit?  I can think of a few
reasons why you might but I don't know if any of them actually matter in
practice.


> > +   }
> > +   return override_color;
> > +}
> > +
> >  /**
> >   * Convert the given color to a bitfield suitable for ORing into DWORD
> 7 of
> >   * SURFACE_STATE (DWORD 12-15 on SKL+).
> > diff --git a/src/mesa/drivers/dri/i965/brw_meta_util.h
> b/src/mesa/drivers/dri/i965/brw_meta_util.h
> > index 4b3408df15..ee0b3bd3e1 100644
> > --- a/src/mesa/drivers/dri/i965/brw_meta_util.h
> > +++ b/src/mesa/drivers/dri/i965/brw_meta_util.h
> > @@ -42,6 +42,11 @@ brw_meta_mirror_clip_and_scissor(const struct
> gl_context *ctx,
> >                                   GLfloat *dstX1, GLfloat *dstY1,
> >                                   bool *mirror_x, bool *mirror_y);
> >
> > +union isl_color_value
> > +gen10_convert_srgb_fast_clear_color(const struct gen_device_info
> *devinfo,
> > +                                    enum isl_format format,
> > +                                    const union isl_color_value color);
> > +
> >  union isl_color_value
> >  brw_meta_convert_fast_clear_color(const struct brw_context *brw,
> >                                    const struct intel_mipmap_tree *mt,
> > diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> > index adf60a840b..315b96e9c4 100644
> > --- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> > +++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> > @@ -51,6 +51,7 @@
> >  #include "intel_buffer_objects.h"
> >
> >  #include "brw_context.h"
> > +#include "brw_meta_util.h"
> >  #include "brw_state.h"
> >  #include "brw_defines.h"
> >  #include "brw_wm.h"
> > @@ -174,7 +175,13 @@ brw_emit_surface_state(struct brw_context *brw,
> >        /* We only really need a clear color if we also have an auxiliary
> >         * surface.  Without one, it does nothing.
> >         */
> > -      clear_color = mt->fast_clear_color;
> > +      if (devinfo->gen >= 10 && isl_format_is_srgb(view.format)) {
> > +         clear_color =
> > +            gen10_convert_srgb_fast_clear_color(devinfo, view.format,
> > +                                                mt->fast_clear_color);
> > +      } else {
> > +         clear_color = mt->fast_clear_color;
> > +      }
> >     }
> >
> >     void *state = brw_state_batch(brw,
> > --
> > 2.14.3
> >
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