* [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init
@ 2018-01-26 9:13 Jia-Ju Bai
2018-01-26 16:13 ` Kalle Valo
2018-01-26 16:26 ` Larry Finger
0 siblings, 2 replies; 5+ messages in thread
From: Jia-Ju Bai @ 2018-01-26 9:13 UTC (permalink / raw)
To: zajec5, hauke; +Cc: linux-wireless, linux-kernel, 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>
---
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);
}
/* Disable to allow reading SPROM. Don't know the adventages of enabling it. */
--
1.7.9.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init
2018-01-26 9:13 [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init Jia-Ju Bai
@ 2018-01-26 16:13 ` Kalle Valo
2018-01-26 16:27 ` Larry Finger
2018-01-26 16:26 ` Larry Finger
1 sibling, 1 reply; 5+ messages in thread
From: Kalle Valo @ 2018-01-26 16:13 UTC (permalink / raw)
To: Jia-Ju Bai; +Cc: zajec5, hauke, linux-wireless, linux-kernel
Jia-Ju Bai <baijiaju1990@gmail.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@gmail.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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init
2018-01-26 9:13 [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init Jia-Ju Bai
2018-01-26 16:13 ` Kalle Valo
@ 2018-01-26 16:26 ` Larry Finger
2018-01-26 16:33 ` Jia-Ju Bai
1 sibling, 1 reply; 5+ messages in thread
From: Larry Finger @ 2018-01-26 16:26 UTC (permalink / raw)
To: Jia-Ju Bai, zajec5, hauke; +Cc: linux-wireless, linux-kernel
On 01/26/2018 03:13 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>
> ---
> 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 have no idea how critical this delay might be, but it would be safer to never
make the sleep be shorter than the original delay. Using (2000, 2500) would be a
better choice of arguments for usleep_range().
NACK
Larry
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init
2018-01-26 16:13 ` Kalle Valo
@ 2018-01-26 16:27 ` Larry Finger
0 siblings, 0 replies; 5+ messages in thread
From: Larry Finger @ 2018-01-26 16:27 UTC (permalink / raw)
To: Kalle Valo, Jia-Ju Bai; +Cc: zajec5, hauke, linux-wireless, linux-kernel
On 01/26/2018 10:13 AM, Kalle Valo wrote:
> Jia-Ju Bai <baijiaju1990@gmail.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@gmail.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.
No ack for this one.
Larry
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init
2018-01-26 16:26 ` Larry Finger
@ 2018-01-26 16:33 ` Jia-Ju Bai
0 siblings, 0 replies; 5+ messages in thread
From: Jia-Ju Bai @ 2018-01-26 16:33 UTC (permalink / raw)
To: Larry Finger, zajec5, hauke; +Cc: linux-wireless, linux-kernel
On 2018/1/27 0:26, Larry Finger wrote:
> On 01/26/2018 03:13 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>
>> ---
>> 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 have no idea how critical this delay might be, but it would be safer
> to never make the sleep be shorter than the original delay. Using
> (2000, 2500) would be a better choice of arguments for usleep_range().
Okay, I have used usleep_range(2000, 2500) and sent patch v2.
Thanks,
Jia-Ju Bai
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-01-26 16:34 UTC | newest]
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2018-01-26 9:13 [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init Jia-Ju Bai
2018-01-26 16:13 ` Kalle Valo
2018-01-26 16:27 ` Larry Finger
2018-01-26 16:26 ` Larry Finger
2018-01-26 16:33 ` Jia-Ju Bai
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