linux-kernel - Re: [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources

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Message-ID: <87y3kkr436.fsf@purkki.adurom.net>
Date:   Fri, 26 Jan 2018 18:13:01 +0200
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     zajec5@...il.com, hauke@...ke-m.de, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init

Jia-Ju Bai <baijiaju1990@...il.com> writes:

> After checking all possible call chains to bcma_pmu_resources_init() here,
> my tool finds that this function is never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with usleep_range to avoid busy wait.
>
> This is found by a static analysis tool named DCNS written by myself.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
> ---
>  drivers/bcma/driver_chipcommon_pmu.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/bcma/driver_chipcommon_pmu.c b/drivers/bcma/driver_chipcommon_pmu.c
> index f1eb4d3..478948c 100644
> --- a/drivers/bcma/driver_chipcommon_pmu.c
> +++ b/drivers/bcma/driver_chipcommon_pmu.c
> @@ -203,7 +203,7 @@ static void bcma_pmu_resources_init(struct bcma_drv_cc *cc)
>  	 * Add some delay; allow resources to come up and settle.
>  	 * Delay is required for SoC (early init).
>  	 */
> -	mdelay(2);
> +	usleep_range(1500, 2000);

I would like to have an ack from someone familiar with bcma before I
apply this.

-- 
Kalle Valo