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

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Message-ID: <CY1PR0301MB08433A2659C75028821F0AE783610@CY1PR0301MB0843.namprd03.prod.outlook.com>
Date:	Tue, 25 Aug 2015 14:54:41 +0000
From:	Shenwei Wang <Shenwei.Wang@...escale.com>
To:	Sudeep Holla <sudeep.holla@....com>
CC:	"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"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



> -----Original Message-----
> From: Sudeep Holla [mailto:sudeep.holla@....com]
> Sent: 2015年8月25日 9:46
> To: Wang Shenwei-B38339
> Cc: Sudeep Holla; shawn.guo@...aro.org; tglx@...utronix.de;
> jason@...edaemon.net; Huang Yongcai-B20788; linux-kernel@...r.kernel.org;
> linux-arm-kernel@...ts.infradead.org
> Subject: Re: [PATCH v9 1/1] irqchip: imx-gpcv2: IMX GPCv2 driver for wakeup
> sources
> 
> 
> 
> On 25/08/15 15:14, Shenwei Wang wrote:
> >
> >
> >> -----Original Message-----
> >> From: Sudeep Holla [mailto:sudeep.holla@....com]
> 
> [...]
> 
> >> I don't see this driver doing anything extra apart from keeping the
> >> wakeup irqs enabled. i.e. You use the same cpu*wake register to
> >> mask/unmask the interrupt as well as set the wakeup source. Since the
> >> wakeup interrupt will be enabled by the driver, you just need to mark
> >> it as wake-up source and nothing extra in the controller right ?
> >> If so, you need to set IRQCHIP_SKIP_SET_WAKE as you are just leaving
> >> that irq enabled and not doing any extra configuration to enable it as wakeup
> source.
> >> Please correct if that wrong, but from the code that's what I could infer.
> >
> > There is no special for this driver. We just use the IRQCHIP driver
> > framework to manage the wakeup sources. Why did you propose to set
> > IRQCHIP_SKIP_SET_WAKE flag here? If you don't need the wakeup feature,
> > you should just not enable this driver in the configuration.
> >
> 
> No, if the driver doesn't nothing extra to configure the wake up source other than
> keeping it enabled, then it fits the case of SKIP_SET_WAKE.
> The driver using this wake would have requested and enabled the irq.
> When it calls enable_irq_wake, you have nothing extra to set(atleast from the
> looks of the driver), so setting SKIP_SET_WAKE will skip the call and updated the
> wake flags in irq core.
> 
> I don't see the real need of 2 separate sets of irq mask being saved in either case.

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.

Regards,
Shenwei

> Regards,
> Sudeep