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

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Message-Id: <20121126202259.190243E09E6@localhost>
Date:	Mon, 26 Nov 2012 20:22:59 +0000
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Rob Herring <robherring2@...il.com>,
	Linus Walleij <linus.walleij@...ricsson.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Stephen Warren <swarren@...dia.com>,
	Anmar Oueja <anmar.oueja@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Russell King <linux@....linux.org.uk>,
	Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH 2/4] irqdomain: augment add_simple() to allocate descs

On Thu, 27 Sep 2012 08:41:53 -0500, Rob Herring <robherring2@...il.com> wrote:
> On 09/27/2012 08:13 AM, Linus Walleij wrote:
> > ---
> >  kernel/irq/irqdomain.c | 21 ++++++++++++++++-----
> >  1 file changed, 16 insertions(+), 5 deletions(-)
> > 
> > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > index 49a7772..a0655b6 100644
> > --- a/kernel/irq/irqdomain.c
> > +++ b/kernel/irq/irqdomain.c
> > @@ -148,7 +148,8 @@ static unsigned int irq_domain_legacy_revmap(struct irq_domain *domain,
> >   * @host_data: Controller private data pointer
> >   *
> >   * Allocates a legacy irq_domain if irq_base is positive or a linear
> > - * domain otherwise.
> > + * domain otherwise. For the legacy domain, IRQ descriptors will also
> > + * be allocated.
> >   *
> >   * This is intended to implement the expected behaviour for most
> >   * interrupt controllers which is that a linear mapping should
> > @@ -162,11 +163,21 @@ struct irq_domain *irq_domain_add_simple(struct device_node *of_node,
> >  					 const struct irq_domain_ops *ops,
> >  					 void *host_data)
> >  {
> > -	if (first_irq > 0)
> > -		return irq_domain_add_legacy(of_node, size, first_irq, 0,
> > +	if (first_irq > 0) {
> > +		int irq_base;
> > +
> > +		irq_base = irq_alloc_descs(first_irq, 0, size, numa_node_id());
> 
> This will always fail for !SPARSE_IRQ, so we probably don't want warn in
> that case. So perhaps something like this:
> 
> int irq_base = first_irq;
> 
> if (is_enabled(CONFIG_SPARSE_IRQ)) {
> 	irq_base = irq_alloc_descs(first_irq, 0, size, numa_node_id());
> 	if (irq_base < 0) {
> 		WARN(1, "Cannot allocate irq_descs @ IRQ%d, assuming pre-allocated\n",
> 		     first_irq);
> 		irq_base = first_irq;
> 	}
> }

Also, warn seems a little over-loud in this case. If the controller is
legitimately claiming irqs in the reserved range, then dumping out a
backtrace is kind of nasty.

g.
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