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radeonsi: rendering to a non-linear XB4H or AB4H buffers causes glitches

More specifically, I tried using a buffer with format XB4H and modifier GFX11,GFX11_256K_R_X,DCC,DCC_RETILE,DCC_INDEPENDENT_64B,DCC_INDEPENDENT_128B,DCC_MAX_COMPRESSED_BLOCK=64B, and AB4H with GFX11,GFX11_256K_R_X,DCC,DCC_PIPE_ALIGN,DCC_INDEPENDENT_128B,DCC_MAX_COMPRESSED_BLOCK=128B. The texture is then read from in a shader and copied to an ARGB2101010 buffer. The result looks like this:

20240322_125402

If I force DRM_FORMAT_MOD_LINEAR, everything works fine.

This was found in https://invent.kde.org/plasma/kwin/-/merge_requests/5437, dunno if it affects any other software.

  • GPU: rx 7900 XTX
  • kernel: 6.8.0-63.fc40.1.x86_64
  • Mesa: 24.0.0 from Fedora 40 repos. I haven't tried newer or older versions yet
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