[Mesa-dev] [PATCH 04/10] i965/skl: skip fast clears for certain surface formats
Ben Widawsky
ben at bwidawsk.net
Tue Nov 3 16:27:44 PST 2015
On Fri, Oct 16, 2015 at 04:05:22PM -0700, Chad Versace wrote:
> On Tue 13 Oct 2015, Ben Widawsky wrote:
> > Initially I had this planned as a patch to be squashed in to the enabling patch
> > because there is no point enabling fast clears without this. However, Chad
> > merged a patch which disables fast clears on gen9 explicitly, and so I can hide
> > this behind the revert of that patch. This is a nice I really wanted this patch
> > as a distinct patch for review. This is a new, weird, and poorly documented
> > restriction for SKL. (In fact, I am still not 100% certain the restriction is
> > entirely necessary, but there are around 30 piglit regressions without this).
> >
> > SKL adds compressible render targets and as a result mutates some of the
> > programming for fast clears and resolves. There is a new internal surface type
> > called the CCS. The old AUX_MCS bit becomes AUX_CCS_D. "The Auxiliary surface is
> > a CCS (Color Control Surface) with compression disabled or an MCS with
> > compression enabled, depending on number of multisamples. MCS (Multisample
> > Control Surface) is a special type of CCS."
> >
> > Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> > ---
> > src/mesa/drivers/dri/i965/brw_context.h | 1 +
> > src/mesa/drivers/dri/i965/brw_surface_formats.c | 27 +++++++++++++++++++++++++
> > src/mesa/drivers/dri/i965/gen8_surface_state.c | 8 ++++++--
> > src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 3 +++
> > 4 files changed, 37 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
> > index e59478a..32b8250 100644
> > --- a/src/mesa/drivers/dri/i965/brw_context.h
> > +++ b/src/mesa/drivers/dri/i965/brw_context.h
> > @@ -1546,6 +1546,7 @@ struct brw_context
> >
> > uint32_t render_target_format[MESA_FORMAT_COUNT];
> > bool format_supported_as_render_target[MESA_FORMAT_COUNT];
> > + bool losslessly_compressable[MESA_FORMAT_COUNT];
>
> I agree with Neil. It's a shame to increase the context size for static
> information. And there is already a static array in
> brw_surface_formats.c for exactly this type of information.
>
As I said in the mail with Neil, the formats aren't static and change per GEN. I
could do the base formats which are shared by all Gens, but I think you still
end up needing something like this. Or did I misunderstand what is being asked
of me?
> >
> > /* Interpolation modes, one byte per vue slot.
> > * Used Gen4/5 by the clip|sf|wm stages. Ignored on Gen6+.
> > diff --git a/src/mesa/drivers/dri/i965/brw_surface_formats.c b/src/mesa/drivers/dri/i965/brw_surface_formats.c
> > index 97fff60..d706ecc 100644
> > --- a/src/mesa/drivers/dri/i965/brw_surface_formats.c
> > +++ b/src/mesa/drivers/dri/i965/brw_surface_formats.c
> > @@ -693,6 +693,33 @@ brw_init_surface_formats(struct brw_context *brw)
> > }
> > }
> >
> > + if (brw->gen >= 9) {
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_FLOAT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_SINT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_UINT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_UNORM16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_SNORM16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_SINT16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_UINT16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_FLOAT16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RG_FLOAT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RG_SINT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RG_UINT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBX_FLOAT16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_B8G8R8A8_UNORM] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_R8G8B8A8_UNORM] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_R8G8B8A8_SNORM] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_SINT8] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RGBA_UINT8] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RG_SINT16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RG_UINT16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_RG_FLOAT16] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_R_UINT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_R_SINT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_R_FLOAT32] = true;
> > + brw->losslessly_compressable[MESA_FORMAT_B8G8R8X8_UNORM] = true;
> > + }
>
> Properties of surface formats should go into the monster table that
> occurs earlier in the file. Then you can replace
> brw_context::losslessly_compressable with a query and keep brw_context
> at its current size.
Same comment from above.
>
> > +
> > /* We will check this table for FBO completeness, but the surface format
> > * table above only covered color rendering.
> > */
> > diff --git a/src/mesa/drivers/dri/i965/gen8_surface_state.c b/src/mesa/drivers/dri/i965/gen8_surface_state.c
> > index 995b4dd..b19b492 100644
> > --- a/src/mesa/drivers/dri/i965/gen8_surface_state.c
> > +++ b/src/mesa/drivers/dri/i965/gen8_surface_state.c
> > @@ -243,8 +243,10 @@ gen8_emit_texture_surface_state(struct brw_context *brw,
> > * "When Auxiliary Surface Mode is set to AUX_CCS_D or AUX_CCS_E, HALIGN
> > * 16 must be used."
> > */
> > - if (brw->gen >= 9 || mt->num_samples == 1)
> > + if (brw->gen >= 9 || mt->num_samples == 1) {
> > assert(mt->halign == 16);
> > + assert(mt->num_samples || brw->losslessly_compressable[mt->format] == true);
> > + }
> > }
> >
> > const uint32_t surf_type = translate_tex_target(target);
> > @@ -488,8 +490,10 @@ gen8_update_renderbuffer_surface(struct brw_context *brw,
> > * "When Auxiliary Surface Mode is set to AUX_CCS_D or AUX_CCS_E, HALIGN
> > * 16 must be used."
> > */
> > - if (brw->gen >= 9 || mt->num_samples == 1)
> > + if (brw->gen >= 9 || mt->num_samples == 1) {
> > assert(mt->halign == 16);
> > + assert(mt->num_samples || brw->losslessly_compressable[mt->format] == true);
>
> This assert is wrong. It's perfectly safe to render into a format that
> is not losslessly compressable, even when it has a MCS.
>
Could you explain how this can happen? I can't really fathom how it can. I am
far from an expert, but I'm also surprised if that's true I never hit the
assert. If/when we support other AUX types this is certainly an invalid
assertion.
> > + }
> > }
> >
> > uint32_t *surf = allocate_surface_state(brw, &offset, surf_index);
> > diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > index 32f0ff7..f108b75 100644
> > --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > @@ -265,6 +265,9 @@ intel_miptree_supports_non_msrt_fast_clear(struct brw_context *brw,
> > if (!brw->format_supported_as_render_target[mt->format])
> > return false;
> >
> > + if (brw->gen >= 9 && !brw->losslessly_compressable[mt->format])
> > + return false;
> > +
>
> This hunk needs a comment that explains why you're disabling 1x fast
> clears for these formats.
>
If you insist on adding a comment, I'd rather add it where the formats are
defined as opposed to here. The variable name, or lookup function would pretty
clearly tell what it's doing. I honestly think only a spec reference is lacking
though.
> > return true;
> > }
> >
> > --
> > 2.6.1
> >
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