From: Ilya Bakoulin Ilya.Bakoulin@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.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 Signed-off-by: Sasha Levin sashal@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 054823d12403..5f1b735da506 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;