Hey, After upgrading to Linux 6.18.0 I noticed that my daisy-chained display setup (Lenovo ThinkPad P16s Gen 4 AMD feeding 3x Dell U2424HE monitors over USB-C for the first, and then daisy-chained MST between them for the rest, running at 1080p@120Hz) would no longer work: displays 2 and 3 in the chain would just show "no DP signal" errors instead.
The same problem also happens on 6.17.10, but 6.17.9 is fine. I bisected it down to https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c?h=v6.17.10&id=18030e84cbda014787369b6d4cde8404fa2d08fc and have confirmed that it 6.17.10 with 18030e84cbda014787369b6d4cde8404fa2d08fc reverted runs fine again, and is able to feed all three monitors. Now, obviously the patch exists for a /reason/, but at the moment it appears to just be trading one miscalculation for another.. would it make sense to revert it for now? Happy to (try to) assist in troubleshooting, but I'm also woefully underinformed about what the numbers are supposed to be instead. Thanks, Natalie Klestrup Röijezon
