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

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Date:	Tue, 15 Sep 2015 18:48:07 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Sudeep Holla <sudeep.holla@....com>,
	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 15/09/15 03:52, Dmitry Torokhov wrote:
> On Mon, Sep 14, 2015 at 4:16 AM, Sudeep Holla <sudeep.holla@....com> wrote:

[...]

>>
>> 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.
>

Fair enough. But I am struggling to understand how this fits into
existing IRQ infrastructure. Few controllers that don't have wakeup
source configuration facility can set IRQCHIP_SKIP_SET_WAKE and just
leave the interrupts enabled in suspend path to wake it up. So IMO,
the above strategy might not work on such controllers.

> 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.

I agree that they are entirely different APIs, I am not sure if we can
support different interrupt controller with such strategy.

Since the irq/pm core handle disabling device IRQs and section "System
Wakeup Interrupts, enable_irq_wake() and disable_irq_wake()" in
Documentation/power/suspend-and-interrupts.txt gives me different
understanding, we can check with tglx on how to handle this.

Regards,
Sudeep
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