linux-kernel - Re: [PATCH] gpu: drm: bridge: adv7511: Replace mdelay with usleep_range in adv7511

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Message-ID: <4cc08136-b05f-89d9-6e6f-dcd12ebc86d3@codeaurora.org>
Date:   Fri, 4 May 2018 11:38:46 +0530
From:   Archit Taneja <architt@...eaurora.org>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     a.hajda@...sung.com, airlied@...ux.ie, daniel.vetter@...ll.ch,
        bhumirks@...il.com, narmstrong@...libre.com, inki.dae@...sung.com,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpu: drm: bridge: adv7511: Replace mdelay with
 usleep_range in adv7511_probe



On Friday 27 April 2018 03:46 AM, Laurent Pinchart wrote:
> Hi Jia-Ju,
> 
> Thank you for the patch.
> 
> On Wednesday, 11 April 2018 11:33:42 EEST Jia-Ju Bai wrote:
>> adv7511_probe() is never called in atomic context.
>> This function is only set as ".probe" in struct i2c_driver.
>>
>> Despite never getting called from atomic context, adv7511_probe()
>> 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.
> 
> Nice work ! Is the tool open-source ?
> 
>> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
>> ---
>>   drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c index b2431ae..2cf7fa1
>> 100644
>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> @@ -1054,7 +1054,7 @@ static int adv7511_probe(struct i2c_client *i2c, const
>> struct i2c_device_id *id) }
>>
>>   	if (adv7511->gpio_pd) {
>> -		mdelay(5);
>> +		usleep_range(5000, 6000);
>>   		gpiod_set_value_cansleep(adv7511->gpio_pd, 0);
>>   	}
> 
> The patch looks good to me.
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

queued to drm-misc-next

Thanks,
Archit