linux-kernel - Re: [PATCH 3/5] drm/msm/dp: Support up to 3 DP controllers

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Date:   Mon, 26 Jul 2021 19:51:17 -0400
From:   Stephen Boyd <swboyd@...omium.org>
To:     Abhinav Kumar <abhinavk@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Kalyan Thota <kalyan_t@...eaurora.org>,
        Kuogee Hsieh <khsieh@...eaurora.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>
Cc:     Rob Herring <robh+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] drm/msm/dp: Support up to 3 DP controllers

Quoting Bjorn Andersson (2021-07-24 21:24:33)
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 59ffd6c8f41f..92b7646a1bb7 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -238,8 +251,11 @@ static int dp_display_bind(struct device *dev, struct device *master,
>         }
>
>         rc = dp_register_audio_driver(dev, dp->audio);
> -       if (rc)
> +       if (rc) {
>                 DRM_ERROR("Audio registration Dp failed\n");
> +               goto end;
> +       }
> +
>
>  end:
>         return rc;

This hunk looks useless. Drop it?

> @@ -1205,6 +1221,26 @@ int dp_display_request_irq(struct msm_dp *dp_display)
>         return 0;
>  }
>
> +static int dp_display_get_id(struct platform_device *pdev)
> +{
> +       const struct msm_dp_config *cfg = of_device_get_match_data(&pdev->dev);
> +       struct resource *res;
> +       int i;
> +
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res)
> +               return -EINVAL;
> +
> +       for (i = 0; i < cfg->num_dp; i++) {
> +               if (cfg->io_start[i] == res->start)
> +                       return i;
> +       }
> +
> +       dev_err(&pdev->dev, "unknown displayport instance\n");
> +       return -EINVAL;
> +}
> +
>  static int dp_display_probe(struct platform_device *pdev)
>  {
>         int rc = 0;
> @@ -1219,6 +1255,10 @@ static int dp_display_probe(struct platform_device *pdev)
>         if (!dp)
>                 return -ENOMEM;
>
> +       dp->id = dp_display_get_id(pdev);
> +       if (dp->id < 0)
> +               return -EINVAL;
> +
>         dp->pdev = pdev;
>         dp->name = "drm_dp";
>
> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
> index e9232032b266..62d54ef6c2c4 100644
> --- a/drivers/gpu/drm/msm/msm_drv.h
> +++ b/drivers/gpu/drm/msm/msm_drv.h
> @@ -161,7 +161,7 @@ struct msm_drm_private {
>         /* DSI is shared by mdp4 and mdp5 */
>         struct msm_dsi *dsi[2];
>
> -       struct msm_dp *dp;
> +       struct msm_dp *dp[3];

It would be nice to either make this dynamically sized (probably little
gain), somehow make a BUILD_BUG_ON(), or have a WARN_ON if
ARRAY_SIZE(dp) is less than a num_dp so we know somebody messed up.