[PATCH v2] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init

[PATCH v2] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init

[Jia-Ju Bai]

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@gmail.com>
---
v2:
* Use usleep_range(2000, 2500), instead of (1500, 2000) in v1.

---
 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(2000, 2500);
 }
 
 /* Disable to allow reading SPROM. Don't know the adventages of enabling it. */
-- 
1.7.9.5

Re: [PATCH v2] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init

[Larry Finger]

On 01/26/2018 10:38 AM, Jia-Ju Bai wrote:
> 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@gmail.com>
> ---
> v2:
> * Use usleep_range(2000, 2500), instead of (1500, 2000) in v1.
> 
> ---
>   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(2000, 2500);

I have no means of testing this patch, but it should be OK.

Acked-by: Larry Finger <Larry.Finger@lwfinger.net>


>   }
>   
>   /* Disable to allow reading SPROM. Don't know the adventages of enabling it. */
> 

Re: [v2] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init

[Kalle Valo]

Jia-Ju Bai <baijiaju1990@gmail.com> wrote:

> 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@gmail.com>
> Acked-by: Larry Finger <Larry.Finger@lwfinger.net>

Patch applied to wireless-drivers-next.git, thanks.

8100091d0248 bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init

-- 
https://patchwork.kernel.org/patch/10186561/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches