drm/msm/dp: stop link training after link training 2 failed

BugLink: https://bugs.launchpad.net/bugs/1969110
[ Upstream commit 9051d629dbf7a998a40f7eac65a9512b01bc3bb8 ]

Each DP link training contains link training 1 followed by link
training 2.  There is maximum of 5 retries of DP link training
before declared link training failed. It is required to stop link
training at end of link training 2 if it is failed so that next
link training 1 can start freshly. This patch fixes link compliance
test  case 4.3.1.13 (Source Device Link Training EQ Fallback Test).

Changes in v10:
--  group into one series

Changes in v11:
-- drop drm/msm/dp: dp_link_parse_sink_count() return immediately if aux read

Fixes: 2e0adc765d88 ("drm/msm/dp: do not end dp link training until video is ready")
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1642531648-8448-5-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 740d2330760e710240c9d89e191686a1d148dda2)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index 62e75dc8afc633c72a01cb7ae9a6ec5223dd383e..4af281d97493f7f6949a32caabc02e5ac07a5207 100644 (file)
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1744,6 +1744,9 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
                                /* end with failure */
                                break; /* lane == 1 already */
                        }
+
+                       /* stop link training before start re training  */
+                       dp_ctrl_clear_training_pattern(ctrl);
                }
        }