The sc7280 eDP sink that supports downspread will fail link training
if source does not enable SSC / downspread. This change will set the
downspread bit in the DP sink if supported and indicate SSC support
to the DP PHY driver.
Signed-off-by: Sankeerth Billakanti <quic_sbillaka@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/dp/dp_ctrl.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index 62e75dc..a40e798 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1228,7 +1228,9 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
int *training_step)
{
int ret = 0;
+ const u8 *dpcd = ctrl->panel->dpcd;
u8 encoding = DP_SET_ANSI_8B10B;
+ u8 ssc;
struct dp_link_info link_info = {0};
dp_ctrl_config_ctrl(ctrl);
@@ -1238,6 +1240,12 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
link_info.capabilities = DP_LINK_CAP_ENHANCED_FRAMING;
dp_aux_link_configure(ctrl->aux, &link_info);
+
+ if (drm_dp_max_downspread(dpcd)) {
+ ssc = DP_SPREAD_AMP_0_5;
+ drm_dp_dpcd_write(ctrl->aux, DP_DOWNSPREAD_CTRL, &ssc, 1);
+ }
+
drm_dp_dpcd_write(ctrl->aux, DP_MAIN_LINK_CHANNEL_CODING_SET,
&encoding, 1);
@@ -1312,9 +1320,11 @@ static int dp_ctrl_enable_mainlink_clocks(struct dp_ctrl_private *ctrl)
struct dp_io *dp_io = &ctrl->parser->io;
struct phy *phy = dp_io->phy;
struct phy_configure_opts_dp *opts_dp = &dp_io->phy_opts.dp;
+ const u8 *dpcd = ctrl->panel->dpcd;
opts_dp->lanes = ctrl->link->link_params.num_lanes;
opts_dp->link_rate = ctrl->link->link_params.rate / 100;
+ opts_dp->ssc = drm_dp_max_downspread(dpcd);
dp_ctrl_set_clock_rate(ctrl, DP_CTRL_PM, "ctrl_link",
ctrl->link->link_params.rate * 1000);
@@ -1406,7 +1416,7 @@ void dp_ctrl_host_deinit(struct dp_ctrl *dp_ctrl)
static bool dp_ctrl_use_fixed_nvid(struct dp_ctrl_private *ctrl)
{
- u8 *dpcd = ctrl->panel->dpcd;
+ const u8 *dpcd = ctrl->panel->dpcd;
/*
* For better interop experience, used a fixed NVID=0x8000
--
2.7.4
