[Mesa-dev] [PATCH] mesa: Match MESA_FORMAT_B5G6R5 for a shallow pixel format of GL_RGB

[Chris Wilson]

If the user supplies a pixel format of GL_RGB + GL_UNSIGNED_SHORT_5_6_5
and specifies a generic unsized GL_RGB internal format, match that to a
texture format of MESA_FORMAT_B5G6R5 if supported by the hardware.

Noticed while playing with mesa-demos/teximage:

  TexImage(RGB/565 256 x 256): 79.8 images/sec, 10.0 MB/sec
  TexSubImage(RGB/565 256 x 256): 3804.9 images/sec, 475.6 MB/sec
  GetTexImage(RGB/565 256 x 256): 99.5 images/sec, 12.4 MB/sec

becomes

  TexImage(RGB/565 256 x 256): 3439.1 images/sec, 429.9 MB/sec
  TexSubImage(RGB/565 256 x 256): 3744.1 images/sec, 468.0 MB/sec
  GetTexImage(RGB/565 256 x 256): 4713.5 images/sec, 589.2 MB/sec

on a puny Baytrail which is still far from what it is capable of. The
reason for the disparity is that the teximage demo uses a busy texture
which is performs an accelerated pixel conversion from the user's B5G6R5
into the native X8B8G8R8. After the patch, no conversion is required
allowing use of the blitter and memcpy fast paths.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 src/mesa/main/texformat.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/mesa/main/texformat.c b/src/mesa/main/texformat.c
index fd9f335..866c7b3 100644
--- a/src/mesa/main/texformat.c
+++ b/src/mesa/main/texformat.c
@@ -114,6 +114,8 @@ _mesa_choose_tex_format(struct gl_context *ctx, GLenum target,
    case GL_RGB:
       if (type == GL_UNSIGNED_INT_2_10_10_10_REV) {
          RETURN_IF_SUPPORTED(MESA_FORMAT_B10G10R10A2_UNORM);
+      } else if (type == GL_UNSIGNED_SHORT_5_6_5) {
+         RETURN_IF_SUPPORTED(MESA_FORMAT_B5G6R5_UNORM);
       }
       /* fallthrough */
    case GL_RGB8:
-- 
2.5.1