linux-kernel - [PATCH v2 2/2] drm/msm/dp: do not stop transmitting phy test pattern during DP phy compliance test

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Message-ID: <1650932213-19162-3-git-send-email-quic_khsieh@quicinc.com>
Date:   Mon, 25 Apr 2022 17:16:53 -0700
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>, <quic_aravindh@...cinc.com>,
        <quic_sbillaka@...cinc.com>, <freedreno@...ts.freedesktop.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 2/2] drm/msm/dp: do not stop transmitting phy test pattern during DP phy compliance test

At normal operation, transmit phy test pattern has to be terminated before
DP controller switch to video ready state. However during phy compliance
testing, transmit phy test pattern should not be terminated until end of
compliance test which usually indicated by unplugged interrupt.

Only stop sending the train pattern in dp_ctrl_on_stream() if we're not
doing compliance testing. We also no longer reset 'p_level' and
'v_level' within dp_ctrl_on_link() due to both 'p_level' and 'v_level'
are acquired from link status at previous dpcd read and we like to use
those level to start link training.

Changes in v2:
-- add more details commit text
-- correct Fixes

Fixes: 2e0adc765d88 ("drm/msm/dp: do not end dp link training until video is ready")
Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index 193cc1a..f99e173 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1699,8 +1699,6 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
 		ctrl->link->link_params.rate,
 		ctrl->link->link_params.num_lanes, ctrl->dp_ctrl.pixel_rate);
 
-	ctrl->link->phy_params.p_level = 0;
-	ctrl->link->phy_params.v_level = 0;
 
 	rc = dp_ctrl_enable_mainlink_clocks(ctrl);
 	if (rc)
@@ -1822,12 +1820,6 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
 		}
 	}
 
-	if (!dp_ctrl_channel_eq_ok(ctrl))
-		dp_ctrl_link_retrain(ctrl);
-
-	/* stop txing train pattern to end link training */
-	dp_ctrl_clear_training_pattern(ctrl);
-
 	ret = dp_ctrl_enable_stream_clocks(ctrl);
 	if (ret) {
 		DRM_ERROR("Failed to start pixel clocks. ret=%d\n", ret);
@@ -1839,6 +1831,13 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
 		return 0;
 	}
 
+	if (!dp_ctrl_channel_eq_ok(ctrl)) {
+		dp_ctrl_link_retrain(ctrl);
+	}
+
+	/* stop txing train pattern to end link training */
+	dp_ctrl_clear_training_pattern(ctrl);
+
 	/*
 	 * Set up transfer unit values and set controller state to send
 	 * video.
-- 
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