linux-kernel - Re: [PATCH 2/7] drm/msm/dp: reduce link rate if failed at link training 1

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Message-ID: <CAE-0n53M1XWa1Ng-+bBLQyKLRzabbTOofOMqknQbF+PWuE6=hw@mail.gmail.com>
Date:   Thu, 15 Jul 2021 20:59:03 +0200
From:   Stephen Boyd <swboyd@...omium.org>
To:     khsieh@...eaurora.org
Cc:     dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run, abhinavk@...eaurora.org, aravindh@...eaurora.org,
        airlied@...ux.ie, daniel@...ll.ch, bjorn.andersson@...aro.org,
        linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/7] drm/msm/dp: reduce link rate if failed at link
 training 1

Quoting khsieh@...eaurora.org (2021-07-09 10:46:41)
> On 2021-07-08 00:33, Stephen Boyd wrote:
> >> +
> >> +static bool dp_ctrl_any_lane_cr_lose(struct dp_ctrl_private *ctrl,
> >> +                                       u8 *cr_status)
> >> +{
> >> +       int i;
> >> +       u8 status;
> >> +       int lane = ctrl->link->link_params.num_lanes;
> >> +
> >> +       for (i = 0; i < lane; i++) {
> >> +               status = cr_status[i / 2];
> >> +               status >>= ((i % 2) * 4);
> >> +               if (!(status & DP_LANE_CR_DONE))
> >> +                       return true;
> >> +       }
> >> +
> >> +       return false;
> >> +}
> >
> > Why not use !drm_dp_clock_recovery_ok() for dp_ctrl_any_lane_cr_lose()?
> ok,
>
> > And then move dp_ctrl_any_lane_cr_done() next to
> > drm_dp_clock_recovery_ok() and call it drm_dp_clock_recovery_any_ok()?
> no understand how it work, can you elaborate it more?

I'm suggesting to make a new function called
drm_dp_clock_recovery_any_ok(), written next to
drm_dp_clock_recovery_ok(). Then call it from here instead of implement
it locally in the qcom DP driver.