For 128b/132b LT prior to LT DPTX should set power state, DP channel
coding and then link rate.
v2: added separate function to avoid code duplication(Jani N)
Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
---
.../drm/i915/display/intel_dp_link_training.c | 62 +++++++++++++------
1 file changed, 44 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index 6aa4ae5e7ebe..e5809cf7d0c4 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -637,6 +637,37 @@ static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp,
return true;
}
+static void
+intel_dp_update_downspread_ctrl(struct intel_dp *intel_dp,
+ const struct intel_crtc_state *crtc_state)
+{
+ u8 link_config[2];
+
+ link_config[0] = crtc_state->vrr.flipline ? DP_MSA_TIMING_PAR_IGNORE_EN : 0;
+ link_config[1] = intel_dp_is_uhbr(crtc_state) ?
+ DP_SET_ANSI_128B132B : DP_SET_ANSI_8B10B;
+ drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config, 2);
+}
+
+static void
+intel_dp_update_link_bw_set(struct intel_dp *intel_dp,
+ const struct intel_crtc_state *crtc_state,
+ u8 link_bw, u8 rate_select)
+{
+ u8 link_config[2];
+
+ /* Write the link configuration data */
+ link_config[0] = link_bw;
+ link_config[1] = crtc_state->lane_count;
+ if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
+ link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
+ drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2);
+ /* eDP 1.4 rate select method. */
+ if (!link_bw)
+ drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET,
+ &rate_select, 1);
+}
+
/*
* Prepare link training by configuring the link parameters. On DDI platforms
* also enable the port here.
@@ -647,7 +678,6 @@ intel_dp_prepare_link_train(struct intel_dp *intel_dp,
{
struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
struct drm_i915_private *i915 = to_i915(encoder->base.dev);
- u8 link_config[2];
u8 link_bw, rate_select;
if (intel_dp->prepare_link_retrain)
@@ -686,23 +716,19 @@ intel_dp_prepare_link_train(struct intel_dp *intel_dp,
drm_dbg_kms(&i915->drm,
"[ENCODER:%d:%s] Using LINK_RATE_SET value %02x\n",
encoder->base.base.id, encoder->base.name, rate_select);
-
- /* Write the link configuration data */
- link_config[0] = link_bw;
- link_config[1] = crtc_state->lane_count;
- if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
- link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
- drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2);
-
- /* eDP 1.4 rate select method. */
- if (!link_bw)
- drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET,
- &rate_select, 1);
-
- link_config[0] = crtc_state->vrr.flipline ? DP_MSA_TIMING_PAR_IGNORE_EN : 0;
- link_config[1] = intel_dp_is_uhbr(crtc_state) ?
- DP_SET_ANSI_128B132B : DP_SET_ANSI_8B10B;
- drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config, 2);
+ if (intel_dp_is_uhbr(crtc_state)) {
+ /*
+ * Spec DP2.1 Section 3.5.2.16
+ * Prior to LT DPTX should set 128b/132b DP Channel coding and then set link rate
+ */
+ intel_dp_update_downspread_ctrl(intel_dp, crtc_state);
+ intel_dp_update_link_bw_set(intel_dp, crtc_state, link_bw,
+ rate_select);
+ } else {
+ intel_dp_update_link_bw_set(intel_dp, crtc_state, link_bw,
+ rate_select);
+ intel_dp_update_downspread_ctrl(intel_dp, crtc_state);
+ }
return true;
}
--
2.25.1
