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

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Message-ID: <alpine.DEB.2.11.1508252123310.15006@nanos>
Date:	Tue, 25 Aug 2015 21:26:20 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Sudeep Holla <sudeep.holla@....com>
cc:	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

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.

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.

Thanks,

	tglx
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