netdev - Re: [PATCH 13/17] net: gianfar: remove misuse of IRQF_NO

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Date:	Wed, 23 Sep 2015 16:20:16 -0500
From:	Li Yang <leoli@...escale.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Manoil Claudiu <claudiu.manoil@...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>,
	"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, Sep 21, 2015 at 11:51 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> 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.

It was not very clear on the intended use of IRQF_NO_SUSPEND at the
beginning as it was not documented anywhere.  It's good that we have
the Documentation/power/suspend-and-interrupts.txt to clarify that
now.

Regards,
Leo
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