5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
[ Upstream commit 319aca883bfa1b85ee08411541b51b9a934ac858 ]
Before re-starting link training reset the link phy params namely
the pre-emphasis and voltage swing levels otherwise the next
link training begins at the previously cached levels which can result
in link training failures.
Fixes: 8ede2ecc3e5e ("drm/msm/dp: Add DP compliance tests on Snapdragon Chipsets")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> # SM8350-HDK
Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Patchwork: https://patchwork.freedesktop.org/patch/605946/
Link: https://lore.kernel.org/r/20240725220450.131245-1-quic_abhinavk@xxxxxxxxxxx
Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/msm/dp/dp_ctrl.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index 854173df67018..85f86afc55052 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1237,6 +1237,8 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
link_info.rate = ctrl->link->link_params.rate;
link_info.capabilities = DP_LINK_CAP_ENHANCED_FRAMING;
+ dp_link_reset_phy_params_vx_px(ctrl->link);
+
dp_aux_link_configure(ctrl->aux, &link_info);
drm_dp_dpcd_write(ctrl->aux, DP_MAIN_LINK_CHANNEL_CODING_SET,
&encoding, 1);
--
2.43.0
