linux-kernel - Re: [PATCH v9 1/1] irqchip: imx-gpcv2: IMX GPCv2 driver for wakeup sources

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Message-ID: <55DD7E40.1040009@arm.com>
Date:	Wed, 26 Aug 2015 09:52:16 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Sudeep Holla <sudeep.holla@....com>,
	Shenwei Wang <Shenwei.Wang@...escale.com>,
	"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	Huang Anson <Anson.Huang@...escale.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v9 1/1] irqchip: imx-gpcv2: IMX GPCv2 driver for wakeup
 sources

Hi Thomas,

On 25/08/15 20:26, Thomas Gleixner wrote:
> On Tue, 25 Aug 2015, Sudeep Holla wrote:
>> On 25/08/15 15:54, Shenwei Wang wrote:
>>> You don't really understand what happens after a driver calls
>>> enable_irq_wake. In suspend state, even the interrupt
>>> controller itself is powered off. How can you get the system up
>>> again  by just using a SKIP_SET_WAKE.
>>
>> Sorry for that, let me try to understand aloud. So you have
>> irq_{un,}mask function that are called when interrupts are enabled and
>> disabled. So suppose you have 3 irqs that are enabled and only one of
>> then is set as wakeup source.
>>
>> Now you call enable_irq_wake, you save that in wakeup_sources, fine.
>> Later when you enter suspend, you save all the 3 active irqs in
>> saved_irq_mask and over-write cpu2wakeup with wakeup_sources, right?
>>
>> All fine, what I am saying is let irq-core know that you want to mask
>> the 2 non-wakeup irqs you have using MASK_ON_SUSPEND. So when
>> suspend_device_irqs is called in suspend path, that's done for you
>> automatically and the cpu2wakeup will have just 1 wakeup enabled which
>> is what you are doing in suspend callback, right ?
>
> I missed that when I reviewed the patch. You are right, it can be
> simplified.
>
>> Now that it's already done for you, you need not do anything extra and
>> hence just set SKIP_SET_WAKE to do nothing.

Thanks for confirming this.

>
> He still needs the set_wake function to capture the wake enabled
> interrupts as they are handed over to the low level asm code via
> imx_gpcv2_get_wakeup_source(). Though they could be read back from the
> hw registers as well.
>

Correct, I have no objection on how it's saved/restored but was against
having 2 different masks and with the approach taken in this patch the
non-wakeup interrupts are enabled until syscore_suspend which is wrong.

There's whole lot of drivers blindly copy pasting this as theme which I
am going through and trying to clean up. I wanted to ensure no more such
additions happen meanwhile, so I am watching such patches closely.

Regards,
Sudeep
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