tree 1cbe5d0869f7a4a7576586769837175b4994f729
parent d71589f290a13bc2aa0d3d847aa8991d815d2f9e
author Eric Yang <Eric.Yang2@amd.com> 1542870426 -0500
committer Alex Deucher <alexander.deucher@amd.com> 1545175511 -0500

drm/amd/display: fix YCbCr420 blank color

[Why]
YCbCr420 packing format uses two chanels for luma, and 1
channel for both chroma component. Our previous implementation
did not account for this and results in every other pixel having
very high luma value, showing greyish color instead of black.

YCbCr444 = <Y1, Cb1, Cr1>; <Y2, Cb2, Cr2> .....
YCbCr420 = <Y1, Y2,  Cb1>; <Y3, Y4,  Cr1> .....

[How]
Program the second channel with the black color value for luma
as well.

Signed-off-by: Eric Yang <Eric.Yang2@amd.com>
Reviewed-by: Hugo Hu <Hugo.Hu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>