linux-kernel - Re: [PATCH v3 3/5] drm/msm/dp: Support up to 3 DP controllers

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Message-ID: <CAE-0n50=EWg1GKuTnRi=zA0ufO1Xg4mucYaqNUZ+wgYNDRcWLA@mail.gmail.com>
Date:   Mon, 4 Oct 2021 20:58:03 -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 v3 3/5] drm/msm/dp: Support up to 3 DP controllers

Quoting Bjorn Andersson (2021-10-01 11:00:56)
> Based on the removal of the g_dp_display and the movement of the
> priv->dp lookup into the DP code it's now possible to have multiple
> DP instances.
>
> In line with the other controllers in the MSM driver, introduce a
> per-compatible list of base addresses which is used to resolve the
> "instance id" for the given DP controller. This instance id is used as
> index in the priv->dp[] array.
>
> Then extend the initialization code to initialize struct drm_encoder for
> each of the registered priv->dp[] and update the logic for associating
> each struct msm_dp with the struct dpu_encoder_virt.
>
> Lastly, bump the number of struct msm_dp instances carries by priv->dp
> to 3, the currently known maximum number of controllers found in a
> Qualcomm SoC.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---

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

Some nits below.

>
> Changes since v2:
> - Added MSM_DRM_DP_COUNT to link the two 3s
> - Moved NULL check for msm_dp_debugfs_init() to the call site
> - Made struct dp_display_private->id unsigned
>
> I also implemented added connector_type to each of the DP instances and
> propagated this to dp_drm_connector_init() but later dropped this again per
> Doug's suggestion that we'll base this on the presence/absence of a associated
> drm bridge or panel.

Sad but OK. We can take up that topic in another patch.

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index f655adbc2421..875b07e7183d 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -203,8 +204,10 @@ static int dpu_kms_debugfs_init(struct msm_kms *kms, struct drm_minor *minor)
>         dpu_debugfs_vbif_init(dpu_kms, entry);
>         dpu_debugfs_core_irq_init(dpu_kms, entry);
>
> -       if (priv->dp)
> -               msm_dp_debugfs_init(priv->dp, minor);
> +       for (i = 0; i < ARRAY_SIZE(priv->dp); i++) {
> +               if (priv->dp[i])
> +                       msm_dp_debugfs_init(priv->dp[i], minor);

This seems to cause a bunch of debugfs warnings when there are multiple
nodes created with the same name.

> +       }
>
>         return dpu_core_perf_debugfs_init(dpu_kms, entry);
>  }
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 5d3ee5ef07c2..ff3477474c5d 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1180,10 +1192,31 @@ int dp_display_request_irq(struct msm_dp *dp_display)
>         return 0;
>  }
>
> +static int dp_display_find_id(struct platform_device *pdev)
> +{
> +       const struct msm_dp_config *cfg = of_device_get_match_data(&pdev->dev);
> +       struct resource *res;
> +       int i;
> +
> +

Nitpick: Remove a newline here.

> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res)
> +               return -EINVAL;
> +
> +       for (i = 0; i < cfg->num_descs; i++) {
> +               if (cfg->io_start[i] == res->start)
> +                       return i;
> +       }

Nitpick: Drop braces on single line if inside for loop.

> +
> +       dev_err(&pdev->dev, "unknown displayport instance\n");
> +       return -EINVAL;
> +}
> +