drm/amd/display: fix link bw calculation for 422 and 420 encoding (cf65ebeb) · Commits · 戴 / test

Link bw required is reduced when we have chroma subsampling. Signed-off-by:

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

+32 −21

Original line number	Diff line number	Diff line
		@@ -1378,6 +1378,11 @@ static uint32_t bandwidth_in_kbps_from_timing(
		{
		uint32_t bits_per_channel = 0;
		uint32_t kbps;

		if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR422)
		bits_per_channel = 12;
		else{

		switch (timing->display_color_depth) {

		case COLOR_DEPTH_666:
		@@ -1401,14 +1406,20 @@ static uint32_t bandwidth_in_kbps_from_timing(
		default:
		break;
		}
		}
		ASSERT(bits_per_channel != 0);

		kbps = timing->pix_clk_khz;
		kbps *= bits_per_channel;

		if (timing->flags.Y_ONLY != 1)
		if (timing->flags.Y_ONLY != 1) {
		/Only YOnly make reduce bandwidth by 1/3 compares to RGB/
		kbps *= 3;
		if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR420)
		kbps /= 2;
		else if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR422)
		kbps = kbps * 2 / 3;
		}

		return kbps;