Mesa (main): mesa/st: always use DXT5 when transcoding ASTC format

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Module: Mesa
Branch: main
Commit: d3b4202b63cb3aca42bc91c5bc416acc1b7f382b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d3b4202b63cb3aca42bc91c5bc416acc1b7f382b

Author: Tapani Pälli <tapani.palli at intel.com>
Date:   Tue Feb 15 10:22:15 2022 +0200

mesa/st: always use DXT5 when transcoding ASTC format

This fixes artifacts seen in games when using ASTC transcoding,
we need to use DXT5 for proper alpha channel support.

Number of components is a block specific property, there is no easy
way to see if we will require >1bit alpha support or not, so simply
use DXT5 to have support in place.

Fixes: 91cbe8d855c ("gallium: Add a transcode_astc driconf option")
Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
Reviewed-by: Nanley Chery <nanley.g.chery at intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15029>

---

 src/mesa/state_tracker/st_format.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/src/mesa/state_tracker/st_format.c b/src/mesa/state_tracker/st_format.c
index 94b387df3b8..a2b6625fbba 100644
--- a/src/mesa/state_tracker/st_format.c
+++ b/src/mesa/state_tracker/st_format.c
@@ -110,23 +110,12 @@ st_mesa_format_to_pipe_format(const struct st_context *st,
    }
 
    if (st_astc_format_fallback(st, mesaFormat)) {
-      const struct util_format_description *desc =
-         util_format_description(mesaFormat);
-
       if (_mesa_is_format_srgb(mesaFormat)) {
-         if (!st->transcode_astc)
-            return PIPE_FORMAT_R8G8B8A8_SRGB;
-         else if (desc->block.width * desc->block.height < 32)
-            return PIPE_FORMAT_DXT5_SRGBA;
-         else
-            return PIPE_FORMAT_DXT1_SRGBA;
+         return st->transcode_astc ? PIPE_FORMAT_DXT5_SRGBA :
+                                     PIPE_FORMAT_R8G8B8A8_SRGB;
       } else {
-         if (!st->transcode_astc)
-            return PIPE_FORMAT_R8G8B8A8_UNORM;
-         else if (desc->block.width * desc->block.height < 32)
-            return PIPE_FORMAT_DXT5_RGBA;
-         else
-            return PIPE_FORMAT_DXT1_RGBA;
+         return st->transcode_astc ? PIPE_FORMAT_DXT5_RGBA :
+                                     PIPE_FORMAT_R8G8B8A8_UNORM;
       }
    }