linux-kernel - RE: [PATCH 13/17] net: gianfar: remove misuse of IRQF_NO

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Date:	Mon, 21 Sep 2015 18:51:31 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Manoil Claudiu <claudiu.manoil@...escale.com>
cc:	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>,
	"David S. Miller" <davem@...emloft.net>,
	Kevin Hao <haokexin@...il.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH 13/17] net: gianfar: remove misuse of IRQF_NO_SUSPEND
 flag

On Mon, 21 Sep 2015, Manoil Claudiu wrote:
> >The device is set as wakeup capable using proper wakeup API but the
> >driver misuses IRQF_NO_SUSPEND to set the interrupt as wakeup source
> >which is incorrect.
> >
> >This patch removes the use of IRQF_NO_SUSPEND flags replacing it with
> >enable_irq_wake instead.
> >
> 
> What would be the purpose of IRQF_NO_SUSPEND flag then?  The flag is a
> friendlier API compared to calling enable_irq_wake().  For older kernels,

It's not an API, it's just a bandaid for lazy programmers.

> on PPC architectures, the flag did the job.  When did this change? Since
> when using IRQF_NO_SUSPEND is a "misuse"?

It always was. Simply because IRQF_NO_SUSPEND has absolutely nothing
to do with wakeup interrupt sources. It's a flag which excludes the
interrupt from the suspend mechanism, but it does not flag it a wakeup
source.

Thanks,

	tglx


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