linux-kernel - Re: [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: <CAE-0n53NJ68H4DD6uE5p2Dhmb9QxGOVXenhdG2=A2_T6Fp520g@mail.gmail.com>
Date:   Tue, 26 Apr 2022 09:48:16 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>, agross@...nel.org,
        airlied@...ux.ie, bjorn.andersson@...aro.org, daniel@...ll.ch,
        dmitry.baryshkov@...aro.org, dri-devel@...ts.freedesktop.org,
        robdclark@...il.com, sean@...rly.run, vkoul@...nel.org
Cc:     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: Re: [PATCH v2 2/2] drm/msm/dp: do not stop transmitting phy test
 pattern during DP phy compliance test

Quoting Kuogee Hsieh (2022-04-25 17:16:53)
> 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>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>

One comment.

> 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
> @@ -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);
> +       }

Drop unnecessary braces.