linux-kernel - Re: [PATCH 1/2] ide: pdc202xx_new: Replace mdelay with usleep_range in detect_pll_input

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Message-ID: <7558e956-62bd-39b9-6ff1-4d5f7ee2c9a3@cogentembedded.com>
Date:   Wed, 11 Apr 2018 11:33:59 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Jia-Ju Bai <baijiaju1990@...il.com>, davem@...emloft.net,
        frankt@...mise.com, andre@...ux-ide.org
Cc:     linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] ide: pdc202xx_new: Replace mdelay with usleep_range
 in detect_pll_input_clock

Hello!

On 4/11/2018 10:52 AM, Jia-Ju Bai wrote:

> detect_pll_input_clock() is never called in atomic context.
> 
> detect_pll_input_clock() is only called by init_chipset_pdcnew(), which
> is set as ".init_chipset" in struct ide_port_info.
> This function is not called in atomic context.
> 
> Despite never getting called from atomic context, detect_pll_input_clock()
> 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/ide/pdc202xx_new.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/ide/pdc202xx_new.c b/drivers/ide/pdc202xx_new.c
> index b33646b..6afa66d 100644
> --- a/drivers/ide/pdc202xx_new.c
> +++ b/drivers/ide/pdc202xx_new.c
> @@ -258,7 +258,7 @@ static long detect_pll_input_clock(unsigned long dma_base)
>   	outb(scr1 | 0x40, dma_base + 0x03);
>   
>   	/* Let the counter run for 10 ms. */
> -	mdelay(10);
> +	usleep_range(10);

    This function takes 2 arguments.

[...]

MBR, Sergei