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

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Date:	Tue, 25 Aug 2015 21:29:49 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Shenwei Wang <Shenwei.Wang@...escale.com>
cc:	Sudeep Holla <sudeep.holla@....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, Shenwei Wang wrote:
> > From: Sudeep Holla [mailto:sudeep.holla@....com]
> > 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 ?
> 
> 	/*
> 	 * Hardware which has no wakeup source configuration facility
> 	 * requires that the non wakeup interrupts are masked at the
> 	 * chip level. The chip implementation indicates that with
> 	 * IRQCHIP_MASK_ON_SUSPEND.
> 	 */
> 	if (irq_desc_get_chip(desc)->flags & IRQCHIP_MASK_ON_SUSPEND)
> 		mask_irq(desc);
> 
> IRQCHIP_MASK_ON_SUSPEND flag is for the hardware that has no wakeup
> source capability.  This GPCv2 block is designed to manage the
> wakeup source, so the flag does not make any sense.

You have no seperate wakeup source mechanism. All you do is to mask all
non wakeup sources and keep the wakeup sources unmask.

That's what happens in gpcv2_wakeup_source_save()

       writel_relaxed(cd->wakeup_sources[i], reg);

So it's the same as letting the core mask all non wakeup sources and
leave the wakeup sources unmask.

> > Now that it's already done for you, you need not do anything extra and hence just
> > set SKIP_SET_WAKE to do nothing.
> 
> static int set_irq_wake_real(unsigned int irq, unsigned int on)
> {
> 	struct irq_desc *desc = irq_to_desc(irq);
> 	int ret = -ENXIO;
> 
> 	if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
> 		return 0;
> 
> 	if (desc->irq_data.chip->irq_set_wake)
> 		ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
> 
> 	return ret;
> }
> From the codes above, if a irqchip can not handle the wakeup
> sources, it can set SKIP flag.  This driver is intended to manage
> the wakeup sources, what's the reason to skip here?

To reduce code. Everything the core can do for you is something you
don't have to implement.

Thanks,

	tglx
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