At least on two MST devices I've tested with, when they are link training downstream, they are totally unable to handle aux ch msgs, so they defer like nuts. I tried 16, it wasn't enough, 32 seems better. This fixes one Dell 4k monitor and one of the MST hubs. v1.1: fixup comment (Tom). Acked-by: Alex Deucher <alexander.deucher@amd.com> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>