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

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Message-ID: <00b11f19-0a4b-df83-923b-001bc5393229@gmail.com>
Date:   Wed, 11 Apr 2018 16:35:55 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.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



On 2018/4/11 16:33, Sergei Shtylyov wrote:
> 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

Oops, sorry for my fault.
Thanks for telling me this :)
I will modify it and send V2.


Best wishes,
Jia-Ju Bai