Glamor chooses texture format that doesn't work on Nexus 4

[Robert Ancell]

When Glamor generates textures it does so with format=GL_RGBA and type=GL_UNSIGNED_BYTE using glTexImage2D. However when it writes to these images it does it with format=GL_BGRA and type = GL_UNSIGNED_INT_8_8_8_8_REV using glTexSubImage2D.

This works fine on a desktop (Intel) but when running on a Nexus 4 a GL_INVALID_OPERATION is generated when calling glTexSubImage2D.

There seems to be a couple of problems:
- The format is originally GL_RGBA and then changed to GL_BGRA. glTexSubImage2D says "GL_INVALID_OPERATION is generated if the texture array has not been defined by a previous glTexImage2D or glCopyTexImage2D operation whose internalformat matches the format of glTexSubImage2D."
- type GL_UNSIGNED_INT_8_8_8_8_REV is an extension and doesn't seem to be supported on the Nexus 4.

By changing the original format to GL_RGBA (in glamor/glamor_utils.h) and the glTexSubImage2D to use format=GL_RGBA type=GL_UNSIGNED_BYTE (glamor/glamor_transfer.c) we can get this to work.

The question is - is the current Glamor code to aggressive in using extensions or should it be able to better detect which method is appropriate for each driver? Are there other issues with the X format the pixmap data is in?

[Daniel van Vugt (vanvugt)]

Blocked by bug 1494240 :(

[Daniel van Vugt (vanvugt)]

Dropped severity. Glamor is not used by default.