Comment 7 for bug 2070096

Here's at least part of the problem.

commit 15c983d0cbb5a158eafb9cb88e6d8dfc4477d9c2
Author: Melissa Wen <email address hidden>
Date: Fri Dec 29 15:25:00 2023 -0100

    drm/amd/display: fix bandwidth validation failure on DCN 2.1

    BugLink: https://bugs.launchpad.net/bugs/2059068

    commit 3a0fa3bc245ef92838a8296e0055569b8dff94c4 upstream.

    IGT `amdgpu/amd_color/crtc-lut-accuracy` fails right at the beginning of
    the test execution, during atomic check, because DC rejects the
    bandwidth state for a fb sizing 64x64. The test was previously working
    with the deprecated dc_commit_state(). Now using
    dc_validate_with_context() approach, the atomic check needs to perform a
    full state validation. Therefore, set fast_validation to false in the
    dc_validate_global_state call for atomic check.

    Cc: <email address hidden>
    Fixes: b8272241ff9d ("drm/amd/display: Drop dc_commit_state in favor of dc_commit_streams")
    Signed-off-by: Melissa Wen <email address hidden>
    Signed-off-by: Hamza Mahfooz <email address hidden>
    Signed-off-by: Alex Deucher <email address hidden>
    Signed-off-by: Greg Kroah-Hartman <email address hidden>
    Signed-off-by: Portia Stephens <email address hidden>
    Signed-off-by: Stefan Bader <email address hidden>

That commit was reverted upstream.

https://github.com/torvalds/linux/commit/c2ab9ce0ee7225fc05f58a6671c43b8a3684f530