From: Ilya Bakoulin <ilya.bakou...@amd.com>
[ Upstream commit 04fb918bf421b299feaee1006e82921d7d381f18 ]
[Why]
Some pixel clock values could cause HDMI TMDS SSCPs to be misaligned
between different HDMI lanes when using YCbCr420 10-bit pixel format.
BIOS functions for transmitter/encoder control take pixel clock in kHz
increments, whereas the function for setting the pixel clock is in 100Hz
increments. Setting pixel clock to a value that is not on a kHz boundary
will cause the issue.
[How]
Round pixel clock down to nearest kHz in 10/12-bpc cases.
Reviewed-by: Aric Cyr <aric....@amd.com>
Acked-by: Brian Chang <brian.ch...@amd.com>
Signed-off-by: Ilya Bakoulin <ilya.bakou...@amd.com>
Tested-by: Daniel Wheeler <daniel.whee...@amd.com>
Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
index 845aa8a1027d..c4040adb88b0 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
@@ -545,9 +545,11 @@ static void dce112_get_pix_clk_dividers_helper (
switch (pix_clk_params->color_depth) {
case COLOR_DEPTH_101010:
actual_pixel_clock_100hz = (actual_pixel_clock_100hz *
5) >> 2;
+ actual_pixel_clock_100hz -= actual_pixel_clock_100hz %
10;
break;
case COLOR_DEPTH_121212:
actual_pixel_clock_100hz = (actual_pixel_clock_100hz *
6) >> 2;
+ actual_pixel_clock_100hz -= actual_pixel_clock_100hz %
10;
break;
case COLOR_DEPTH_161616:
actual_pixel_clock_100hz = actual_pixel_clock_100hz * 2;
--
2.35.1
