[PATCH 19/45] drm/amd/display: fix YCbCr420 blank color

[sunpeng.li at amd.com]

From: Eric Yang <Eric.Yang2 at amd.com>

[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 at amd.com>
Reviewed-by: Hugo Hu <Hugo.Hu at amd.com>
Acked-by: Leo Li <sunpeng.li at amd.com>
---
 drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c | 11 ++++++++++-
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c   |  9 +++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
index 8ac54bc..e947cc5 100644
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
@@ -1264,10 +1264,19 @@ static void program_scaler(const struct dc *dc,
 		pipe_ctx->plane_res.scl_data.lb_params.depth,
 		&pipe_ctx->stream->bit_depth_params);
 
-	if (pipe_ctx->stream_res.tg->funcs->set_overscan_blank_color)
+	if (pipe_ctx->stream_res.tg->funcs->set_overscan_blank_color) {
+		/*
+		 * The way 420 is packed, 2 channels carry Y component, 1 channel
+		 * alternate between Cb and Cr, so both channels need the pixel
+		 * value for Y
+		 */
+		if (pipe_ctx->stream->timing.pixel_encoding == PIXEL_ENCODING_YCBCR420)
+			color.color_r_cr = color.color_g_y;
+
 		pipe_ctx->stream_res.tg->funcs->set_overscan_blank_color(
 				pipe_ctx->stream_res.tg,
 				&color);
+	}
 
 	pipe_ctx->plane_res.xfm->funcs->transform_set_scaler(pipe_ctx->plane_res.xfm,
 		&pipe_ctx->plane_res.scl_data);
diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
index 2432a5d..613293d 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
@@ -2160,6 +2160,15 @@ static void dcn10_blank_pixel_data(
 	color_space = stream->output_color_space;
 	color_space_to_black_color(dc, color_space, &black_color);
 
+	/*
+	 * The way 420 is packed, 2 channels carry Y component, 1 channel
+	 * alternate between Cb and Cr, so both channels need the pixel
+	 * value for Y
+	 */
+	if (stream->timing.pixel_encoding == PIXEL_ENCODING_YCBCR420)
+		black_color.color_r_cr = black_color.color_g_y;
+
+
 	if (stream_res->tg->funcs->set_blank_color)
 		stream_res->tg->funcs->set_blank_color(
 				stream_res->tg,
-- 
2.7.4