linux-kernel - Re: [PATCH 2/4 v2] irqdomain: augment add

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Date:	Tue, 27 Nov 2012 01:13:47 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	Linus Walleij <linus.walleij@...ricsson.com>,
	linux-kernel@...r.kernel.org,
	Rob Herring <rob.herring@...xeda.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Anmar Oueja <anmar.oueja@...aro.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	Russell King <linux@....linux.org.uk>,
	Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH 2/4 v2] irqdomain: augment add_simple() to allocate descs

On Mon, Nov 26, 2012 at 9:26 PM, Grant Likely <grant.likely@...retlab.ca> wrote:

>> +                     if (irq_base < 0) {
>> +                             WARN(1, "Cannot allocate irq_descs @ IRQ%d, assuming pre-allocated\n",
>> +                                  first_irq);
>> +                             irq_base = first_irq;
>
> As I just commented on the previous version, WARN() is probably too
> verbose (and scary). Make it an informational.

So the discussion began with me removing exactly that kind of WARN()
from arch/arm/common/gic.c:
http://marc.info/?l=linux-arm-kernel&m=134860088710574&w=2

Which was NACKed by Rob:
http://marc.info/?l=linux-arm-kernel&m=134860136515611&w=2
Who prefered to leave it in to encourage platforms to get fixed.

This code just follows exactly that pattern.

I'm happy to patch out *both* (or rather patch gic.c to use
irq_domain_add_simple()) because I never quite liked
it in the first place.

> However, I see another problem. What is the requested range straddles
> the boundary between reserved and non-reserved IRQs? It would be good to
> give some information about which irq range was requested and maybe
> report which ones were available.... or check to see if the request is
> inside or partially inside the reserved region?

Right now the usual symptom of that is that the system hangs.

Do you mean we should probe around a bit with
irq_get_next_irq() to figure out more precisely what the
problem is, or did you have something more elegant
in mind?

Yours,
Linus Walleij
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