linux-kernel - [PATCH v3] drm/msm/dp: delete DP_RECOVERED_CLOCK_OUT

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Message-ID: <1660252761-14595-1-git-send-email-quic_khsieh@quicinc.com>
Date:   Thu, 11 Aug 2022 14:19:21 -0700
From:   Kuogee Hsieh <quic_khsieh@...cinc.com>
To:     <robdclark@...il.com>, <sean@...rly.run>, <swboyd@...omium.org>,
        <dianders@...omium.org>, <vkoul@...nel.org>, <daniel@...ll.ch>,
        <airlied@...ux.ie>, <agross@...nel.org>,
        <dmitry.baryshkov@...aro.org>, <bjorn.andersson@...aro.org>
CC:     <quic_aravindh@...cinc.com>, <quic_khsieh@...cinc.com>,
        <quic_sbillaka@...cinc.com>, <freedreno@...ts.freedesktop.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] drm/msm/dp: delete DP_RECOVERED_CLOCK_OUT_EN to fix tps4

Data Symbols scrambled is required for tps4 at link training 2.
Therefore SCRAMBLING_DISABLE bit should not be set for tps4 to
work.

RECOVERED_CLOCK_OUT_EN is for enable simple EYE test for jitter
measurement with minimal equipment for embedded applications purpose
and is not required to be set during normal operation.
Current implementation always have RECOVERED_CLOCK_OUT_EN bit set
which cause SCRAMBLING_DISABLE bit wrongly set at tps4 which prevent
tps4 from working.

This patch delete setting RECOVERED_CLOCK_OUT_EN to fix SCRAMBLING_DISABLE
be wrongly set at tps4.

Changes in v2:
-- fix Fixes tag

Changes in v3:
-- revise commit text

Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>

Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
Reviewed-by: Stephen Boyd <swboyd@...omium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index ab6aa13..013ca02 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1214,7 +1214,7 @@ static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
 	if (ret)
 		return ret;
 
-	dp_ctrl_train_pattern_set(ctrl, pattern | DP_RECOVERED_CLOCK_OUT_EN);
+	dp_ctrl_train_pattern_set(ctrl, pattern);
 
 	for (tries = 0; tries <= maximum_retries; tries++) {
 		drm_dp_link_train_channel_eq_delay(ctrl->aux, ctrl->panel->dpcd);
-- 
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