linux-kernel - Re: [PATCH v2 3/5] drm/msm/dp: Refactor ioremap wrapper

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Message-ID: <CAE-0n53ZVf7E0q_cMEmuQH7q+xytRd-pjerrNnoVHBwqGMr6ZA@mail.gmail.com>
Date:   Thu, 26 Aug 2021 01:19:16 +0000
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>,
        Rob Clark <robdclark@...il.com>,
        Rob Herring <robh+dt@...nel.org>, Sean Paul <sean@...rly.run>
Cc:     Kuogee Hsieh <khsieh@...eaurora.org>,
        Tanmay Shah <tanmay@...eaurora.org>,
        Chandan Uddaraju <chandanu@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/5] drm/msm/dp: Refactor ioremap wrapper

Quoting Bjorn Andersson (2021-08-25 15:25:55)
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
> index c064ced78278..215065336268 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.c
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.c
> @@ -19,40 +19,30 @@ static const struct dp_regulator_cfg sdm845_dp_reg_cfg = {
>         },
>  };
>
> -static int msm_dss_ioremap(struct platform_device *pdev,
> -                               struct dss_io_data *io_data)
> +static void __iomem *dp_ioremap(struct platform_device *pdev, int idx, size_t *len)
>  {
> -       struct resource *res = NULL;
> +       struct resource *res;
>
> -       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, idx);
>         if (!res) {
>                 DRM_ERROR("%pS->%s: msm_dss_get_res failed\n",
>                         __builtin_return_address(0), __func__);

This error can be removed too, right? At least I thought passing in NULL
as 'res' to devm_ioremap_resource() did that. It actually looks like we
can use devm_platform_get_and_ioremap_resource() and then pass in &res

	base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
	if (!IS_ERR(base))
		*len = resource_size(res);

	return base;

> -               return -ENODEV;
> +               return ERR_PTR(-ENODEV);
>         }
>
> -       io_data->len = (u32)resource_size(res);
> -       io_data->base = devm_ioremap(&pdev->dev, res->start, io_data->len);
> -       if (!io_data->base) {
> -               DRM_ERROR("%pS->%s: ioremap failed\n",
> -                       __builtin_return_address(0), __func__);
> -               return -EIO;
> -       }
> -
> -       return 0;
> +       *len = resource_size(res);
> +       return devm_ioremap_resource(&pdev->dev, res);
>  }
>
>  static int dp_parser_ctrl_res(struct dp_parser *parser)
>  {
> -       int rc = 0;
>         struct platform_device *pdev = parser->pdev;
>         struct dp_io *io = &parser->io;
> +       struct dss_io_data *dss = &io->dp_controller;
>
> -       rc = msm_dss_ioremap(pdev, &io->dp_controller);
> -       if (rc) {
> -               DRM_ERROR("unable to remap dp io resources, rc=%d\n", rc);
> -               return rc;
> -       }
> +       dss->base = dp_ioremap(pdev, 0, &dss->len);
> +       if (IS_ERR(dss->base))
> +               return PTR_ERR(dss->base);
>
>         io->phy = devm_phy_get(&pdev->dev, "dp");
>         if (IS_ERR(io->phy))
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
> index 34b49628bbaf..dc62e70b1640 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.h
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.h
> @@ -26,7 +26,7 @@ enum dp_pm_type {
>  };
>
>  struct dss_io_data {
> -       u32 len;
> +       size_t len;

len is a resource_size_t above, not sure if that really matters in
practice to indicate it here though.

>         void __iomem *base;
>  };
>