linux-kernel - Re: [PATCH 1/3] mmc: wbsd: Replace mdelay with usleep_range in wbsd

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Date:   Wed, 11 Apr 2018 17:04:14 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     Pierre Ossman <pierre@...man.eu>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] mmc: wbsd: Replace mdelay with usleep_range in wbsd_init

On 11 April 2018 at 04:46, Jia-Ju Bai <baijiaju1990@...il.com> wrote:
> wbsd_init() is never called in atomic context.
>
> The call chains ending up at wbsd_init() are:
> [1] wbsd_init() <- wbsd_probe()
> [2] wbsd_init() <- wbsd_pnp_probe()
>
> wbsd_probe() is set as ".probe" in struct platform_driver.
> wbsd_pnp_probe() is set as ".probe" in struct pnp_driver.
> These functions are not called in atomic context.
>
> Despite never getting called from atomic context, wbsd_init()
> calls mdelay() to busily wait.
> This is not necessary and can be replaced with usleep_range() to
> avoid busy waiting.
>
> This is found by a static analysis tool named DCNS written by myself.
> And I also manually check it.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>

The patch is good, however I think you should squash all three in this
series into one. For obvious reasons.

Kind regards
Uffe

> ---
>  drivers/mmc/host/wbsd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/wbsd.c b/drivers/mmc/host/wbsd.c
> index 546aaf8..6224d12 100644
> --- a/drivers/mmc/host/wbsd.c
> +++ b/drivers/mmc/host/wbsd.c
> @@ -1709,7 +1709,7 @@ static int wbsd_init(struct device *dev, int base, int irq, int dma,
>         /*
>          * Allow device to initialise itself properly.
>          */
> -       mdelay(5);
> +       usleep_range(5000, 6000);
>
>         /*
>          * Reset the chip into a known state.
> --
> 1.9.1
>