linux-kernel - [PATCH v18 4/4] drm/msm/dp: stop link training after link training 2 failed

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Date:   Tue, 18 Jan 2022 10:47:28 -0800
From:   Kuogee Hsieh <quic_khsieh@...cinc.com>
To:     <dri-devel@...ts.freedesktop.org>, <robdclark@...il.com>,
        <sean@...rly.run>, <swboyd@...omium.org>, <vkoul@...nel.org>,
        <daniel@...ll.ch>, <airlied@...ux.ie>, <agross@...nel.org>,
        <dmitry.baryshkov@...aro.org>, <bjorn.andersson@...aro.org>
CC:     Kuogee Hsieh <quic_khsieh@...cinc.com>,
        <quic_abhinavk@...cinc.com>, <aravindh@...eaurora.org>,
        <quic_sbillaka@...cinc.com>, <freedreno@...ts.freedesktop.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v18 4/4] drm/msm/dp: stop link training after link training 2 failed

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@...cinc.com>
Reviewed-by: Stephen Boyd <swboyd@...omium.org>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index f98df93..245e1b9 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1755,6 +1755,9 @@ 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);
 		}
 	}
 
-- 
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