linux-kernel - Re: [PATCH v2] extcon: usb-gpio: Don't miss event during suspend/resume

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Message-id: <570AF062.5000609@samsung.com>
Date:	Mon, 11 Apr 2016 09:31:30 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Roger Quadros <rogerq@...com>, myungjoo.ham@...sung.com
Cc:	linux-kernel@...r.kernel.org,
	Grygorii Strashko <grygorii.strashko@...com>
Subject: Re: [PATCH v2] extcon: usb-gpio: Don't miss event during suspend/resume

Hi Roger,

On 2016년 04월 08일 16:34, Roger Quadros wrote:
> Pin state might have changed during suspend/resume while
> our interrupts were disabled and if device doesn't support wakeup.
> 
> Scan for change during resume for such case.
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
> v2:
> - only check for state change during resume if device wakeup is not supported
> 
>  drivers/extcon/extcon-usb-gpio.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
> index bc61d11..118f8ab 100644
> --- a/drivers/extcon/extcon-usb-gpio.c
> +++ b/drivers/extcon/extcon-usb-gpio.c
> @@ -185,6 +185,8 @@ static int usb_extcon_resume(struct device *dev)
>  	int ret = 0;
>  
>  	enable_irq(info->id_irq);
> +	if (!device_may_wakeup(dev))
> +		usb_extcon_detect_cable(&info->wq_detcable.work);

The device_may_wakeup() check the following two states:
- dev->power.can_wakeup - device_init_wakeup() function set the this field.
- dev->power.wakeup - device_wakeup_enable() function set the this field.

The probe function of extcon-usb-gpio.c always call the 'device_init_wakeup(dev,true).
But, anywhere in extcon-usb-gpio.c don't handle the device_wakeup_enable() for dev->power.wakeup.

In the extcon-usb-gpio.c, device_may_wakeup(dev) return always 'false'.
If you use the only device_may_wakeup(),
device_may_wakeup() is not able to check whether interrupt is wakeup source or not.

Thanks,
Chanwoo Choi