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Message-ID: <488f0db0-6fa9-8a66-f055-f2cc57470a47@quicinc.com>
Date: Mon, 1 Aug 2022 13:18:35 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Kuogee Hsieh <quic_khsieh@...cinc.com>, <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_sbillaka@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
<quic_aravindh@...cinc.com>, <freedreno@...ts.freedesktop.org>
Subject: Re: [Freedreno] [PATCH v2] drm/msm/dp: delete
DP_RECOVERED_CLOCK_OUT_EN to fix tps4
On 8/1/2022 1:13 PM, Kuogee Hsieh wrote:
> 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
>
> Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
This is a good catch !
Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
> 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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