linux-kernel - RE: [PATCH 04/17] powerpc: mpic: use IRQCHIP_SKIP_SET_WAKE instead of redundant mpic_irq_set

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Date:	Wed, 23 Sep 2015 05:49:10 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Wang Dongsheng <Dongsheng.Wang@...escale.com>
cc:	Scott Wood <scottwood@...escale.com>,
	Sudeep Holla <sudeep.holla@....com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Hongtao Jia <hongtao.jia@...escale.com>,
	Marc Zyngier <marc.zyngier@....com>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: RE: [PATCH 04/17] powerpc: mpic: use IRQCHIP_SKIP_SET_WAKE instead
 of redundant mpic_irq_set_wake

On Wed, 23 Sep 2015, Wang Dongsheng wrote:
> > On Mon, 2015-09-21 at 16:47 +0100, Sudeep Holla wrote:
> > > mpic_irq_set_wake return -ENXIO for non FSL MPIC and sets IRQF_NO_SUSPEND
> > > flag for FSL ones. enable_irq_wake already returns -ENXIO if irq_set_wak
> > > is not implemented. Also there's no need to set the IRQF_NO_SUSPEND flag
> > > as it doesn't guarantee wakeup for that interrupt.
> > >
> 
> Non-freescale return -ENXIO, is there any issue? If non-freescale
> platform does not support it, but IPs still use
> enable/disable_irq_wake, we should return a error number.

You can just set IRQCHIP_SKIP_SET_WAKE for FSL chips and not for the
others.

> @Scott:
> If set this flag we cannot keep a irq as a wakeup source when system going to
> SUSPEND or MEM.
> 
> irq_set_wake() means we can set this irq as a wake source.
> IRQCHIP_SKIP_SET_WAKE is ignore irq_set_wake() feature.

Nonsense. IRQCHIP_SKIP_SET_WAKE merily tells the core not to bail on
!chip->irq_set_wake(), but its still marking the interrupt as wakeup
source and therefor not masking it on suspend.

IRQF_NO_SUSPEND is the wrong tool. End of story.

Thanks,

	tglx
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