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drm/amd/display: fix link bw calculation for 422 and 420 encoding

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Link bw required is reduced when we have chroma subsampling.

Signed-off-by: Eric Yang <Eric.Yang2@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Eric Yang 2018-03-23 13:56:16 -04:00 • committed by Alex Deucher
parent 3dc8acad23
commit cf65ebeb68
1 changed files with 32 additions and 21 deletions
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53
drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
View file

@ -1378,37 +1378,48 @@ static uint32_t bandwidth_in_kbps_from_timing(
{
uint32_t bits_per_channel = 0;
uint32_t kbps;
switch (timing->display_color_depth) {
case COLOR_DEPTH_666:
bits_per_channel = 6;
break;
case COLOR_DEPTH_888:
bits_per_channel = 8;
break;
case COLOR_DEPTH_101010:
bits_per_channel = 10;
break;
case COLOR_DEPTH_121212:
if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR422)
bits_per_channel = 12;
break;
case COLOR_DEPTH_141414:
bits_per_channel = 14;
break;
case COLOR_DEPTH_161616:
bits_per_channel = 16;
break;
default:
break;
else{
switch (timing->display_color_depth) {
case COLOR_DEPTH_666:
bits_per_channel = 6;
break;
case COLOR_DEPTH_888:
bits_per_channel = 8;
break;
case COLOR_DEPTH_101010:
bits_per_channel = 10;
break;
case COLOR_DEPTH_121212:
bits_per_channel = 12;
break;
case COLOR_DEPTH_141414:
bits_per_channel = 14;
break;
case COLOR_DEPTH_161616:
bits_per_channel = 16;
break;
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;