netdev - Re: [PATCH V4 2/2] net: ethernet: ravb: Enable optional refclk

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Date:   Tue, 13 Apr 2021 09:33:23 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Adam Ford <aford173@...il.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Adam Ford-BE <aford@...conembedded.com>,
        Sergei Shtylyov <sergei.shtylyov@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V4 2/2] net: ethernet: ravb: Enable optional refclk

Hi Adam,

On Mon, Apr 12, 2021 at 3:27 PM Adam Ford <aford173@...il.com> wrote:
> For devices that use a programmable clock for the AVB reference clock,
> the driver may need to enable them.  Add code to find the optional clock
> and enable it when available.
>
> Signed-off-by: Adam Ford <aford173@...il.com>
> Reviewed-by: Andrew Lunn <andrew@...n.ch>
>
> ---
> V4:  Eliminate the NULL check when disabling refclk, and add a line
>      to disable the refclk if there is a failure after it's been
>      initialized.

Thanks for the update!

> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -2148,6 +2148,13 @@ static int ravb_probe(struct platform_device *pdev)
>                 goto out_release;
>         }
>
> +       priv->refclk = devm_clk_get_optional(&pdev->dev, "refclk");
> +       if (IS_ERR(priv->refclk)) {
> +               error = PTR_ERR(priv->refclk);
> +               goto out_release;

Note that this will call clk_disable_unprepare() in case of failure, which is
fine, as that function is a no-op in case of a failed clock.

> +       }
> +       clk_prepare_enable(priv->refclk);
> +
>         ndev->max_mtu = 2048 - (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN);
>         ndev->min_mtu = ETH_MIN_MTU;
>
> @@ -2244,6 +2251,7 @@ static int ravb_probe(struct platform_device *pdev)
>         if (chip_id != RCAR_GEN2)
>                 ravb_ptp_stop(ndev);
>  out_release:
> +       clk_disable_unprepare(priv->refclk);
>         free_netdev(ndev);
>
>         pm_runtime_put(&pdev->dev);

Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds