From 304c95fcd7774a792869d31e7003c752a4414529 Mon Sep 17 00:00:00 2001
From: Ilya Bakoulin <Ilya.Bakoulin@amd.com>
Date: Tue, 26 Jul 2022 16:19:38 -0400
Subject: drm/amd/display: Fix pixel clock programming
Git-commit: 04fb918bf421b299feaee1006e82921d7d381f18
Patch-mainline: v6.0-rc2
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849
[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@amd.com>
Acked-by: Brian Chang <Brian.Chang@amd.com>
Signed-off-by: Ilya Bakoulin <Ilya.Bakoulin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
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 213de8cabfad..165392380842 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
@@ -543,9 +543,11 @@ 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;
--
2.38.1