This is a note to let you know that I've just added the patch titled
drm/amd/display: Fix pixel clock programming
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amd-display-fix-pixel-clock-programming.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 262513aa5386b304dedb17c265197c770e9b9b32
Author: Ilya Bakoulin <Ilya.Bakoulin@xxxxxxx>
Date: Tue Jul 26 16:19:38 2022 -0400
drm/amd/display: Fix pixel clock programming
[ 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.Cyr@xxxxxxx>
Acked-by: Brian Chang <Brian.Chang@xxxxxxx>
Signed-off-by: Ilya Bakoulin <Ilya.Bakoulin@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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 eca67d5d5b10d..721be82ccebec 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
@@ -546,9 +546,11 @@ 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;
