[Mesa-dev] [Mesa-stable] [PATCH] amd/common/gfx9: workaround DCC corruption more conservatively

[Marek Olšák]

Reviewed-by: Marek Olšák <marek.olsak at amd.com>

Marek

On Thu, Oct 12, 2017 at 11:24 AM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> Fixes KHR-GL45.texture_swizzle.smoke and others on Vega.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102809
> Cc: mesa-stable at lists.freedesktop.org
> ---
>  src/amd/common/ac_surface.c | 32 +++++++++++++++++++++++++-------
>  1 file changed, 25 insertions(+), 7 deletions(-)
>
> diff --git a/src/amd/common/ac_surface.c b/src/amd/common/ac_surface.c
> index 22c653f0c4f..ea348211787 100644
> --- a/src/amd/common/ac_surface.c
> +++ b/src/amd/common/ac_surface.c
> @@ -917,23 +917,25 @@ static int gfx9_compute_miptree(ADDR_HANDLE addrlib,
>         } else {
>                 /* DCC */
>                 if (!(surf->flags & RADEON_SURF_DISABLE_DCC) &&
>                     !(surf->flags & RADEON_SURF_SCANOUT) &&
>                     !compressed &&
>                     in->swizzleMode != ADDR_SW_LINEAR &&
>                     /* TODO: We could support DCC with MSAA. */
>                     in->numSamples == 1) {
>                         ADDR2_COMPUTE_DCCINFO_INPUT din = {0};
>                         ADDR2_COMPUTE_DCCINFO_OUTPUT dout = {0};
> +                       ADDR2_META_MIP_INFO meta_mip_info[RADEON_SURF_MAX_LEVELS] = {};
>
>                         din.size = sizeof(ADDR2_COMPUTE_DCCINFO_INPUT);
>                         dout.size = sizeof(ADDR2_COMPUTE_DCCINFO_OUTPUT);
> +                       dout.pMipInfo = meta_mip_info;
>
>                         din.dccKeyFlags.pipeAligned = 1;
>                         din.dccKeyFlags.rbAligned = 1;
>                         din.colorFlags = in->flags;
>                         din.resourceType = in->resourceType;
>                         din.swizzleMode = in->swizzleMode;
>                         din.bpp = in->bpp;
>                         din.unalignedWidth = in->width;
>                         din.unalignedHeight = in->height;
>                         din.numSlices = in->numSlices;
> @@ -945,35 +947,51 @@ static int gfx9_compute_miptree(ADDR_HANDLE addrlib,
>                         if (ret != ADDR_OK)
>                                 return ret;
>
>                         surf->u.gfx9.dcc.rb_aligned = din.dccKeyFlags.rbAligned;
>                         surf->u.gfx9.dcc.pipe_aligned = din.dccKeyFlags.pipeAligned;
>                         surf->u.gfx9.dcc_pitch_max = dout.pitch - 1;
>                         surf->dcc_size = dout.dccRamSize;
>                         surf->dcc_alignment = dout.dccRamBaseAlign;
>                         surf->num_dcc_levels = in->numMipLevels;
>
> -                       /* Disable DCC for the smallest levels. It seems to be
> -                        * required for DCC readability between CB and shaders
> -                        * when TC L2 isn't flushed. This was guessed.
> +                       /* Disable DCC for levels that are in the mip tail.
> +                        *
> +                        * There are two issues that this is intended to
> +                        * address:
> +                        *
> +                        * 1. Multiple mip levels may share a cache line. This
> +                        *    can lead to corruption when switching between
> +                        *    rendering to different mip levels because the
> +                        *    RBs don't maintain coherency.
> +                        *
> +                        * 2. Texturing with metadata after rendering sometimes
> +                        *    fails with corruption, probably for a similar
> +                        *    reason.
> +                        *
> +                        * Working around these issues for all levels in the
> +                        * mip tail may be overly conservative, but it's what
> +                        * Vulkan does.
>                          *
>                          * Alternative solutions that also work but are worse:
> -                        * - Disable DCC.
> +                        * - Disable DCC entirely.
>                          * - Flush TC L2 after rendering.
>                          */
> -                       for (unsigned i = 1; i < in->numMipLevels; i++) {
> -                               if (mip_info[i].pitch *
> -                                   mip_info[i].height * surf->bpe < 1024) {
> +                       for (unsigned i = 0; i < in->numMipLevels; i++) {
> +                               if (meta_mip_info[i].inMiptail) {
>                                         surf->num_dcc_levels = i;
>                                         break;
>                                 }
>                         }
> +
> +                       if (!surf->num_dcc_levels)
> +                               surf->dcc_size = 0;
>                 }
>
>                 /* FMASK */
>                 if (in->numSamples > 1) {
>                         ADDR2_COMPUTE_FMASK_INFO_INPUT fin = {0};
>                         ADDR2_COMPUTE_FMASK_INFO_OUTPUT fout = {0};
>
>                         fin.size = sizeof(ADDR2_COMPUTE_FMASK_INFO_INPUT);
>                         fout.size = sizeof(ADDR2_COMPUTE_FMASK_INFO_OUTPUT);
>
> --
> 2.11.0
>
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