Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
In-Reply-To: <1626191647-13901-8-git-send-email-khsieh@codeaurora.org>
References: <1626191647-13901-1-git-send-email-khsieh@codeaurora.org> <1626191647-13901-8-git-send-email-khsieh@codeaurora.org>
From:   Stephen Boyd <swboyd@chromium.org>
User-Agent: alot/0.9.1
Date:   Thu, 22 Jul 2021 19:14:21 +0000
Message-ID: <CAE-0n525b3V9D+aT_xwHQK-g6SjAXse4j7f1wHQHzeL3EEFV_w@mail.gmail.com>
Subject: Re: [PATCH v2 7/7] drm/msm/dp: retrain link when loss of symbol lock detected
To:     Kuogee Hsieh <khsieh@codeaurora.org>,
        dri-devel@lists.freedesktop.org, robdclark@gmail.com,
        sean@poorly.run
Cc:     abhinavk@codeaurora.org, aravindh@codeaurora.org, airlied@linux.ie,
        daniel@ffwll.ch, bjorn.andersson@linaro.org,
        linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Quoting Kuogee Hsieh (2021-07-13 08:54:07)
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 6a013b0..20951c8 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1638,6 +1638,25 @@ static bool dp_ctrl_clock_recovery_any_ok(
>         return drm_dp_clock_recovery_ok(link_status, lane_count);
>  }
>
> +static bool dp_ctrl_loss_symbol_lock(struct dp_ctrl_private *ctrl)
> +{
> +       u8 link_status[DP_LINK_STATUS_SIZE];
> +       u8 status;
> +       int i;
> +       int num_lanes = ctrl->link->link_params.num_lanes;
> +
> +       dp_ctrl_read_link_status(ctrl, link_status);
> +
> +       for (i = 0; i < num_lanes; i++) {
> +               status = link_status[i / 2];
> +               status >>= ((i % 2) * 4);
> +               if (!(status & DP_LANE_SYMBOL_LOCKED))
> +                       return true;
> +       }
> +
> +       return false;
> +}

Can this function move to drivers/gpu/drm/drm_dp_helper.c and be called
drm_dp_symbol_locked()?

> +
>  int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
>  {
>         int rc = 0;