The normal suspend-resume path doesn't seem to be enough (I end up hitting [0] and [1] actually). However, if I force it to take the reset path (using amdgpu_device_lock_reset_domain()/amdgpu_device_unlock_reset_domain()), that does seem to do the trick.
[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c?h=v6.19-rc7#n3161 [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c?h=v6.19-rc7#n3171
