linux-kernel - RE: [PATCH v8 1/2] irqchip: imx-gpcv2: IMX GPCv2 driver for wakeup sources

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Message-ID: <BY1PR0301MB0839B8F390ABA092FB80362083620@BY1PR0301MB0839.namprd03.prod.outlook.com>
Date:	Mon, 24 Aug 2015 18:25:07 +0000
From:	Shenwei Wang <Shenwei.Wang@...escale.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Huang Anson <Anson.Huang@...escale.com>
Subject: RE: [PATCH v8 1/2] irqchip: imx-gpcv2: IMX GPCv2 driver for wakeup
 sources



> -----Original Message-----
> From: Thomas Gleixner [mailto:tglx@...utronix.de]
> > > > +static int gpcv2_wakeup_source_save(void) {
> > > > +	struct gpcv2_irqchip_data *cd;
> > > > +	void __iomem *reg;
> > > > +	int i;
> > > > +
> > > > +	cd = imx_gpcv2_instance;
> > > > +	if (!cd)
> > > > +		return 0;
> > > > +
> > > > +	for (i = 0; i < IMR_NUM; i++) {
> > > > +		reg = cd->gpc_base + cd->cpu2wakeup + i * 4;
> > > > +		cd->enabled_irqs[i] = readl_relaxed(reg);
> > >
> > > You read the full state of the register and restore the full state.
> > > So why enabled_irqs?
> >
> > There are two user scenarios:
> > In CPU Idle state, the system need to be woke up by any enabled irqs,
> > not just the ones that marked as wakeup sources.
> > In Suspend State, they system will only be woke up by the one that
> > marked as a wakeup source.  Enabled_irqs are used to save the values
> > before suspend, and restore them after resume.
> 
> That's what you want achieve. Still you save the full content of the registers and
> restore the full content. That saves/restores the enabled and disabled interrupts.
> So enabled_irqs is a misnomer as you save the full state.

How about change its name to "saved_irq_mask"?

> > > set_wake() or leave it when they want to have resume functionality?
> > >
> > Each time system goes into the suspend state, it will call set_wake
> > (ON) again to configure the wakeup sources. Clearing wakeup_sources
> > here can make sure the system work as expected no matter that a driver
> > calls set_wake (OFF) during resume stage.
> 
> We rather make sure that the drivers call set_wake(OFF) as they are supposed to,
> because if they do not then the set_wake(ON) logic in the core code will see the
> counter != 0 and not invoke the irq callback.

Sounds reasonable. Then I will remove this line in new patch.

Thanks,
Shenwei

> Thanks,
> 
> 	tglx
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