issue: the UMC6 h/w bug is that when MCLK is doing the switch in the middle of a page access being preempted by high priority client (e.g. DISPLAY) then UMC and the mclk switch would stuck there due to deadlock how: fixed by disabling auto PreChg for UMC to avoid high priority client preempting other client's access on the same page, thus the deadlock could be avoided v2: put the patch in callback of UMC6 v3: rename the callback to "init_registers" Signed-off-by: Monk Liu <Monk.Liu@amd.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Reviewed-by: Hawking Zhang <hawking.zhang@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>