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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <570B8CE7.3060605@ti.com>
Date:	Mon, 11 Apr 2016 14:39:19 +0300
From:	Roger Quadros <rogerq@...com>
To:	Chanwoo Choi <cw00.choi@...sung.com>,
	Grygorii Strashko <grygorii.strashko@...com>,
	<myungjoo.ham@...sung.com>
CC:	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] extcon: usb-gpio: Don't miss event during
 suspend/resume

Chanwoo,

On 11/04/16 14:12, Chanwoo Choi wrote:
> On 2016년 04월 11일 17:37, Grygorii Strashko wrote:
>> On 04/11/2016 03:31 AM, Chanwoo Choi wrote:
>>> 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.
>>
>>
>> device_init_wakeup()
>>  |-> device_wakeup_enable()
>>
>>>
>>> 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.
>>>
>>
>> This check is correct and it also will take into account wake up settings changes
>> which can be made through sysfs: /sys/.../devX/power/wakeup
>>
> 
> To Grygorii,
> 
> You're right. I was mistaken. Again, I analyzed the sequence about wakeup.
> Thanks for your reply.
> 
> 1. Register device as wakeup_source.
>  device_init_wakeup(dev, true) on probe()
> 	device_wakeup_enable(dev)
> 		device_source_register(const char *name)
> 			struct wakeup_source *ws;
> 			ws = wakeup_source_create(name)
> 			if (ws)
> 				wakeup_source_add(ws);
> 					...
> 					list_add_rcu(&ws->entry, &wakeup_sources);
> 					...
> 			return ws;
> 			
> 			
> 2. Register the interrupt as wake_irq
> dev_pm_set_wake_irq(struct device *dev, int irq) on probe()
> 	struct wake_irq *wirq;
> 	wirq->dev = dev;
> 	wirq->irq = irq;
> 	dev_pm_attach_wake_irq(dev, irq, wirq);
> 		device_wakeup_attach_irq(*dev, *wakeirq)
> 			struct wakeup_source *ws;
> 			ws = dev->power.wakeup;
> 			ws->wakeirq = wakeirq;
> 
> 
> 3. Enable irq wake if device is already registed to wakeup_sources.
> dpm_suspend_noirq()
> 	device_wakeup_arm_wake_irqs()
> 		list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
> 			if (ws->wakeirq)
> 				dev_pm_arm_wake_irq(sw->wakeirq);
> 					if (device_may_wakeup(wirq->dev))
> 						enable_irq_wake(wirq->irq);
> 
> 
> To Roger,
> 
> How about using the queue_delayed_work() instead of direct call function?
> Because the spent time of wakeup from suspend state should be fast.
> So, I think that you better to use the queue_delayed_work().
> 
> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
> index 118f8ab3be73..f6cbdfe31519 100644
> --- a/drivers/extcon/extcon-usb-gpio.c
> +++ b/drivers/extcon/extcon-usb-gpio.c
> @@ -186,7 +186,9 @@ static int usb_extcon_resume(struct device *dev)
>  
>         enable_irq(info->id_irq);
>         if (!device_may_wakeup(dev))
> -               usb_extcon_detect_cable(&info->wq_detcable.work);
> +               queue_delayed_work(system_power_efficient_wq,
> +                               &info->wq_detcable,
> +                               info->debounce_jiffies);

Why not to just use queue_work() instead of queue_delayed_work()
as don't need to debounce the input?

cheers,
-roger

>  
>         return ret;
>  }