util/format: Add an RGB planar format for YV12, like we have for NV12.

Turnip will use this for mapping the to the corresponding hardware format,
and we could also extend mesa/st to avoid adding extra samplers for
external image sampling of YV12 on freedreno.

Reviewed-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13046>

src/gallium/include/pipe/p_format.h

@@ -504,6 +504,7 @@ enum pipe_format {
    PIPE_FORMAT_XYUV,
 
    PIPE_FORMAT_R8_G8B8_420_UNORM,
+   PIPE_FORMAT_R8_G8_B8_420_UNORM,
 
    PIPE_FORMAT_B8G8R8X8_SNORM,
    PIPE_FORMAT_B8G8R8X8_UINT,

src/util/format/u_format.csv

@@ -397,9 +397,10 @@ PIPE_FORMAT_IYUV                  , planar3, 1, 1, 1,     ,     ,     ,     , xy
 PIPE_FORMAT_NV12                  , planar2, 1, 1, 1,     ,     ,     ,     , xyzw, yuv
 PIPE_FORMAT_NV21                  , planar2, 1, 1, 1,     ,     ,     ,     , xyzw, yuv
 
-# RGB version of NV12 for hardware that supports sampling from
+# RGB version of NV12 and YV12 for hardware that supports sampling from
 # multiplane textures but needs color-space conversion in the shader.
 PIPE_FORMAT_R8_G8B8_420_UNORM     , planar2, 1, 1, 1,  un8,     ,     ,     , xyzw, rgb
+PIPE_FORMAT_R8_G8_B8_420_UNORM    , planar3, 1, 1, 1,  un8,     ,     ,     , xyzw, rgb
 
 PIPE_FORMAT_Y8_U8_V8_422_UNORM    , planar3, 1, 1, 1,     ,     ,     ,     , xyzw, yuv
 PIPE_FORMAT_Y8_U8V8_422_UNORM     , planar2, 1, 1, 1,     ,     ,     ,     , xyzw, yuv

src/util/format/u_format_table.py

@@ -109,6 +109,7 @@ def has_access(format):
         'y16_u16v16_422_unorm',
         'y16_u16_v16_444_unorm',
         'r8_g8b8_420_unorm',
+        'r8_g8_b8_420_unorm',
     ]
     if format.short_name() in noaccess_formats:
         return False