linux-kernel - Re: [PATCH] mtd: nand: diskonchip: Replace mdelay with usleep_range in doc

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Message-ID: <20180422192650.45fcfa4e@bbrezillon>
Date:   Sun, 22 Apr 2018 19:26:50 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     boris.brezillon@...e-electrons.com, richard@....at,
        dwmw2@...radead.org, computersforpeace@...il.com,
        marek.vasut@...il.com, cyrille.pitchen@...ev4u.fr,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: nand: diskonchip: Replace mdelay with usleep_range
 in doc_probe

On Wed, 11 Apr 2018 10:57:57 +0800
Jia-Ju Bai <baijiaju1990@...il.com> wrote:

> doc_probe() is never called in atomic context.
> 
> doc_probe() is only called by init_nanddoc(), which is only set as 
> a parameter of module_init().
> This function is not called in atomic context.
> 
> Despite never getting called from atomic context, doc_probe()
> 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>
> ---
>  drivers/mtd/nand/diskonchip.c | 4 ++--

Applied to nand/next after fixing the subject prefix and the file path.

Thanks,

Boris

>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/diskonchip.c b/drivers/mtd/nand/diskonchip.c
> index c3aa53c..2679bc4 100644
> --- a/drivers/mtd/nand/diskonchip.c
> +++ b/drivers/mtd/nand/diskonchip.c
> @@ -1482,12 +1482,12 @@ static int __init doc_probe(unsigned long physadr)
>  		WriteDOC(tmp, virtadr, Mplus_DOCControl);
>  		WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);
>  
> -		mdelay(1);
> +		usleep_range(1000, 2000);
>  		/* Enable the Millennium Plus ASIC */
>  		tmp = DOC_MODE_NORMAL | DOC_MODE_MDWREN | DOC_MODE_RST_LAT | DOC_MODE_BDECT;
>  		WriteDOC(tmp, virtadr, Mplus_DOCControl);
>  		WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);
> -		mdelay(1);
> +		usleep_range(1000, 2000);
>  
>  		ChipID = ReadDOC(virtadr, ChipID);
>