drm/amd/display: Use DTBCLK as refclk instead of DPREFCLK

[ 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 <alvin.lee2@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Austin Zheng <austin.zheng@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>

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 ffbb739d85b6923aacf49024b2925928709a1149..8496ff4a25e359d463a5dc0b3d21e93f5ddebe0f 100644 (file)
--- 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) {