When using TexStorage with sRGB formats, the sRGB part is ignored and the texture behaves as if it was created with the non-sRGB counterpart of the format.
- if I create a texture with TexStorage and then fill it with CompressedTexSubImage, GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT will behave exactly as GL_COMPRESSED_RGBA_S3TC_DXT1_EXT.
- if I create and fill a texture with CompressedTexImage, GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT and GL_COMPRESSED_RGBA_S3TC_DXT1_EXT will behave differently.
This problem does not occur on NVIDIA machines, so I'm guessing it's an AMD driver bug.
Edit: it seems that it's even more broken that that.. AFAIK
TexStorage2D(GL_TEXTURE_2D, 1, GL_DEPTH24_STENCIL8, 1024, 1024);
should work as a drop-in replacement for
TexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, 1024, 1024, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
but in practice it doesn't work (i.e. it returns the same value everywhere when sampling). Again, working correctly on NVIDIA.