linux-kernel - Re: [PATCH 0/5] Fix regression introduced by set_irq

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Message-ID: <20151020141736.GX32532@n2100.arm.linux.org.uk>
Date:	Tue, 20 Oct 2015 15:17:36 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc:	Jason Cooper <jason@...edaemon.net>,
	Lior Amsalem <alior@...vell.com>, Andrew Lunn <andrew@...n.ch>,
	Tawfik Bayouk <tawfik@...vell.com>,
	Marc Zyngier <marc.zyngier@....com>,
	linux-kernel@...r.kernel.org, Nadav Haklai <nadavh@...vell.com>,
	Gregory Clement <gregory.clement@...e-electrons.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-arm-kernel@...ts.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Subject: Re: [PATCH 0/5] Fix regression introduced by set_irq_flags() removal

On Tue, Oct 20, 2015 at 04:08:28PM +0200, Thomas Petazzoni wrote:
> As discussed on IRC, another simpler (code line wise) solution is to
> simply clear the IRQ_NOAUTOEN flag in the irq-armada-370-xp, which
> brings us back to what set_irq_flags() was doing, without actually
> reverting Rob's patch.
> 
> However, relying on IRQ_NOAUTOEN being cleared doesn't seem like the
> right long term solution, which is why I implemented what I believe is
> a (hopefully) better long term solution.

However, this is rather worrying.  NOAUTOEN is supposed to avoid enabling
the interrupt when the interrupt is claimed.

If, as a result of Rob's patch, we now have a load of IRQs which are
marked with NOAUTOEN which weren't, that's quite a large regression -
possibly one which hasn't been properly found (not everyone tests -rc
kernels) and we may be better to revert Rob's patch to avoid lots of
breakge being reported when 4.3 is released.

I think Rob's patches need another review in light of this, to determine
how much breakage there is here, and a decision how to proceed made on
that basis.

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