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

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Date:	Tue, 22 Sep 2015 16:09:48 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Manoil Claudiu <claudiu.manoil@...escale.com>,
	Thomas Gleixner <tglx@...utronix.de>
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 22/09/15 15:04, Manoil Claudiu wrote:
>> -----Original Message-----
>> From: Thomas Gleixner [mailto:tglx@...utronix.de]

[...]

>>> 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.
>>
>
> I'm seeing also a "powerpc: mpic" patch in the series, unfortunately I can't

Yes I think that was a redundant code, so I removed it. IIRC it was
setting IRQF_NO_SUSPEND in irq_set_wake callback which again is incorrect.

> afford to test it right now. However I ran a quick test with this gianfar patch
> in isolation on a powerpc system, and seen some difference in the behavior
> (with and w/o the patch).  In both cases the system wakes up from standby
> by magic packet.  However, without the IRQF_NO_SUSPEND flag 2 wake-up
> interrupts are reported in /proc/interrupts for one magic packet; with the

OK that's interesting, will have check if I have similar behavior on my
setup too.

> flag on there's just 1 interrupt.  Maybe this is not relevant, maybe the
> "powerpc: mpic" patch from this series changes this behavior.

Hmm not sure, but better to test it together if possible. If required we
can reorder for bisect-ability reasons.

> But if this is the API, what can I say? We'll see in time.  Btw, enable_irq_wake()
> returns an error code, normally it should be handled by printing a warning
> message at least, right?  But since most drivers don't handle that, I'm assuming
> it should be left unhandled to avoid overcomplicating things.

Yes I left it so that I can add if the maintainer insist and not churn
too much code adding warning.

> FWIW
> Acked-by: Claudiu Manoil <claudiu.manoil@...escale.com>
>

Thanks.

Regards,
Sudeep
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