lkml.org 
[lkml]   [2018]   [Apr]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] net: dsa: b53: Replace mdelay with msleep in b53_switch_reset_gpio
From
Date
On 04/11/2018 12:14 AM, Jia-Ju Bai wrote:
>
>
> On 2018/4/11 13:30, Phil Reid wrote:
>> On 11/04/2018 09:51, Jia-Ju Bai wrote:
>>> b53_switch_reset_gpio() is never called in atomic context.
>>>
>>> The call chain ending up at b53_switch_reset_gpio() is:
>>> [1] b53_switch_reset_gpio() <- b53_switch_reset() <-
>>>     b53_reset_switch() <- b53_setup()
>>>
>>> b53_switch_reset_gpio() is set as ".setup" in struct dsa_switch_ops.
>>> This function is not called in atomic context.
>>>
>>> Despite never getting called from atomic context,
>>> b53_switch_reset_gpio()
>>> calls mdelay() to busily wait.
>>> This is not necessary and can be replaced with msleep() 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@gmail.com>
>>> ---
>>>   drivers/net/dsa/b53/b53_common.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/dsa/b53/b53_common.c
>>> b/drivers/net/dsa/b53/b53_common.c
>>> index 274f367..e070ff6 100644
>>> --- a/drivers/net/dsa/b53/b53_common.c
>>> +++ b/drivers/net/dsa/b53/b53_common.c
>>> @@ -597,10 +597,10 @@ static void b53_switch_reset_gpio(struct
>>> b53_device *dev)
>>>       /* Reset sequence: RESET low(50ms)->high(20ms)
>>>        */
>>>       gpio_set_value(gpio, 0);
>>> -    mdelay(50);
>>> +    msleep(50);
>>>         gpio_set_value(gpio, 1);
>>> -    mdelay(20);
>>> +    msleep(20);
>>>         dev->current_page = 0xff;
>>>   }
>>>
>> Would that also imply gpio_set_value could be gpio_set_value_cansleep?
>>
>
> Yes, I think gpio_set_value_cansleep() is okay here?
> Do I need to send a V2 patch to replace gpio_set_value()?

Yes, I would lump these two changes in the same patch since this is
effectively about solving sleeping vs. non sleeping operations.

Thanks!
--
Florian

\
 
 \ /
  Last update: 2018-04-11 18:19    [W:0.044 / U:0.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site