We only need to register once OS calls the interrupt control. Also, if we are entering static screen mode, disable after ramping is done. Disable shall be done via timer of 2 seconds regardless of ramping complete or not, just to simplify. Also, ramp to mid instead of min, due to better flicker performance... Signed-off-by: Anthony Koo <Anthony.Koo@amd.com> Reviewed-by: Aric Cyr <Aric.Cyr@amd.com> Acked-by: Harry Wentland <harry.wentland@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>