linux-kernel - Re: [PATCH] Enable clock before calling clk_get

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Message-Id: <4863111525100577@web2o.yandex.ru>
Date:   Mon, 30 Apr 2018 18:02:57 +0300
From:   Evgeniy Polyakov <zbr@...emap.net>
To:     Stefan Potyra <stefan.potyra@...ktrobit.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     "ldv-project@...uxtesting.org" <ldv-project@...uxtesting.org>,
        "sil2review@...ts.osadl.org" <sil2review@...ts.osadl.org>
Subject: Re: [PATCH] Enable clock before calling clk_get_rate() on it.

Hi Stefan

Nice catch, thank you!

19.04.2018, 16:02, "Stefan Potyra" <stefan.potyra@...ktrobit.com>:
> According to the API, you may only call clk_get_rate() after actually
> enabling it.
>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Fixes: a5fd9139f74c w1: add 1-wire master driver for i.MX27 / i.MX31
> Signed-off-by: Stefan Potyra <Stefan.Potyra@...ktrobit.com>

Acked-by: Evgeniy Polyakov <zbr@...emap.net>

Greg, please pull it into your tree. Is this a stable material?

> ---
>  drivers/w1/masters/mxc_w1.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/w1/masters/mxc_w1.c b/drivers/w1/masters/mxc_w1.c
> index 74f2e6e6202a..a9599027d4ef 100644
> --- a/drivers/w1/masters/mxc_w1.c
> +++ b/drivers/w1/masters/mxc_w1.c
> @@ -112,6 +112,10 @@ static int mxc_w1_probe(struct platform_device *pdev)
>          if (IS_ERR(mdev->clk))
>                  return PTR_ERR(mdev->clk);
>
> + err = clk_prepare_enable(mdev->clk);
> + if (err)
> + return err;
> +
>          clkrate = clk_get_rate(mdev->clk);
>          if (clkrate < 10000000)
>                  dev_warn(&pdev->dev,
> @@ -128,10 +132,6 @@ static int mxc_w1_probe(struct platform_device *pdev)
>          if (IS_ERR(mdev->regs))
>                  return PTR_ERR(mdev->regs);
>
> - err = clk_prepare_enable(mdev->clk);
> - if (err)
> - return err;
> -
>          /* Software reset 1-Wire module */
>          writeb(MXC_W1_RESET_RST, mdev->regs + MXC_W1_RESET);
>          writeb(0, mdev->regs + MXC_W1_RESET);
> --
> 2.17.0