From: Austin Zheng <[email protected]>

[ Upstream commit 4a30cc2bd281fa176a68b5305cd3695d636152ad ]

[Why]
Flash of corruption observed when UCLK switching after transitioning
from DTBCLK to DPREFCLK on subVP(DP) + subVP(HDMI) config
Scenario where DPREFCLK is required instead of DTBCLK is not expected

[How]
Always set the DTBCLK source as DTBCLK0

Reviewed-by: Alvin Lee <[email protected]>
Acked-by: Tom Chung <[email protected]>
Signed-off-by: Austin Zheng <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c 
b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c
index ffbb739d85b69..8496ff4a25e35 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c
@@ -290,7 +290,8 @@ static void dccg32_set_dpstreamclk(
        struct dcn_dccg *dccg_dcn = TO_DCN_DCCG(dccg);
 
        /* set the dtbclk_p source */
-       dccg32_set_dtbclk_p_src(dccg, src, otg_inst);
+       /* always program refclk as DTBCLK. No use-case expected to require 
DPREFCLK as refclk */
+       dccg32_set_dtbclk_p_src(dccg, DTBCLK0, otg_inst);
 
        /* enabled to select one of the DTBCLKs for pipe */
        switch (dp_hpo_inst) {
-- 
2.40.1

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