On link training failure retry link training with a lesser link
rate/lane count as specified in the DP spec.
Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_ddi.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index ed7620e7f763..29d785a4b904 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -2502,6 +2502,7 @@ static void mtl_ddi_pre_enable_dp(struct intel_atomic_state *state,
crtc_state->port_clock,
crtc_state->lane_count);
+retry:
/*
* We only configure what the register value will be here. Actual
* enabling happens during link training farther down.
@@ -2586,7 +2587,14 @@ static void mtl_ddi_pre_enable_dp(struct intel_atomic_state *state,
* Pattern, wait for 5 idle patterns (DP_TP_STATUS Min_Idles_Sent)
* (timeout after 800 us)
*/
- intel_dp_start_link_train(intel_dp, crtc_state);
+ if (!intel_dp_start_link_train(intel_dp, crtc_state)) {
+ /* Link Training failed, retain */
+ intel_dp->link_trained = false;
+ intel_dp_stop_link_train(intel_dp, crtc_state);
+ encoder->post_disable(state, encoder,
+ crtc_state, conn_state);
+ goto retry;
+ }
/* 6.n Set DP_TP_CTL link training to Normal */
if (!is_trans_port_sync_mode(crtc_state))
--
2.25.1
