linux-kernel - Re: [PATCH v4] pinctrl: mediatek: Implement wake handler and suspend resume

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Date:	Mon, 14 Sep 2015 19:52:41 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	maoguang meng <maoguang.meng@...iatek.com>,
	Hongzhou Yang <hongzhou.yang@...iatek.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Daniel Kurtz <djkurtz@...omium.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" 
	<linux-mediatek@...ts.infradead.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Yingjoe Chen (陳英洲) 
	<Yingjoe.Chen@...iatek.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4] pinctrl: mediatek: Implement wake handler and suspend resume

On Mon, Sep 14, 2015 at 4:16 AM, Sudeep Holla <sudeep.holla@....com> wrote:
>
>
> On 12/09/15 10:50, maoguang meng wrote:
>> hi Sudeep:
>>
>> I test flowlling your blow suggestions,but the system can not be woken.
>>
>> beacuse,mtk_eint_suspend will mask it.As we know if eint wakeup system
>> it must be unmasked before enter suspend flow.
>>
>> e.x
>>
>> static int __maybe_unused elan_suspend(struct device *dev)
>> {
>>       struct i2c_client *client = to_i2c_client(dev);
>>       struct elan_tp_data *data = i2c_get_clientdata(client);
>>       int ret;
>>
>>       /*
>>        * We are taking the mutex to make sure sysfs operations are
>>        * complete before we attempt to bring the device into low[er]
>>        * power mode.
>>        */
>>       ret = mutex_lock_interruptible(&data->sysfs_mutex);
>>       if (ret)
>>               return ret;
>>
>>       disable_irq(client->irq);
>>
>>       if (device_may_wakeup(dev)) {
>>               ret = elan_sleep(data);
>>               /* Enable wake from IRQ */
>>               data->irq_wake = (enable_irq_wake(client->irq) == 0);
>
> This is wrong assumption in the driver. enable_irq_wake doesn't
> implicitly enable the IRQ. So the disable_irq should be moved to else.
> And the resume patch also needs to be fixed accordingly, otherwise you
> may get unbalanced irq. But this should not be the reason for fixing the
> pinctrl suspend/resume.
>

Elan driver does not want to enable servicing IRQs, it just wants to
configure them as wakeup sources. Hence the current elan_suspend() is
fine. When system wakes up and the device is resumed and the driver is
ready to service interrupts it will enable IRQ again.

IOW enable_irq_wake() and enable_irq() are 2 completely different
calls and it is perfectly fine to disable IRQ and then ebale it as a
wakeup source.

Thanks.

-- 
Dmitry
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