linux-kernel - Re: [PATCH v2 6/9] irqchip / gic: Add stacked irqdomain support for ACPI based GICv2 init

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Date:	Tue, 23 Jun 2015 18:38:45 +0100
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Hanjun Guo <hanjun.guo@...aro.org>
Cc:	Marc Zyngier <Marc.Zyngier@....com>,
	Jason Cooper <jason@...edaemon.net>,
	Will Deacon <Will.Deacon@....com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Arnd Bergmann <arnd@...db.de>,
	Tomasz Nowicki <tomasz.nowicki@...aro.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Olof Johansson <olof@...om.net>, Wei Huang <wei@...hat.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH v2 6/9] irqchip / gic: Add stacked irqdomain support for
 ACPI based GICv2 init

On Tue, Jun 23, 2015 at 04:11:38PM +0100, Hanjun Guo wrote:

[...]

> >> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> >> index 8fc67bc..d1b2131 100644
> >> --- a/drivers/irqchip/irq-gic.c
> >> +++ b/drivers/irqchip/irq-gic.c
> >> @@ -851,15 +851,22 @@ static struct notifier_block gic_cpu_notifier = {
> >>   static int gic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
> >>   				unsigned int nr_irqs, void *arg)
> >>   {
> >> -	int i, ret;
> >> +	int i;
> >>   	irq_hw_number_t hwirq;
> >> -	unsigned int type = IRQ_TYPE_NONE;
> >> -	struct of_phandle_args *irq_data = arg;
> >>
> >> -	ret = gic_irq_domain_xlate(domain, irq_data->np, irq_data->args,
> >> -				   irq_data->args_count, &hwirq, &type);
> >> -	if (ret)
> >> -		return ret;
> >> +	if (domain->of_node) {	/* DT case */
> >> +		int ret;
> >> +		unsigned int type = IRQ_TYPE_NONE;
> >> +		struct of_phandle_args *irq_data = arg;
> >> +
> >> +		ret = gic_irq_domain_xlate(domain, irq_data->np,
> >> +					irq_data->args,
> >> +					irq_data->args_count, &hwirq, &type);
> >> +		if (ret)
> >> +			return ret;
> >> +	} else {	/* ACPI case */
> >> +		hwirq = (irq_hw_number_t)*(u32 *)arg;
> >> +	}
> >
> > If domain->of_node is NULL and system booted with DT the code above
> > does not fail (and if it fails almost certainly that won't be graceful)
> > but it should.
> 
> how about the following logic?
> 
> if (!domain->of_node && acpi_disabled)
> 	return -ENODEV;
> else if (domain->of_node)
> 	dt related code;
> else
> 	ACPI related code;

Code is not checking the node at present so:

if (acpi_disabled)
	dt code;
else
	ACPI code;

would do, but that's a nit.

> >>   	for (i = 0; i < nr_irqs; i++)
> >>   		gic_irq_domain_map(domain, virq + i, hwirq + i);
> >> @@ -945,11 +952,11 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
> >>   		gic_irqs = 1020;
> >>   	gic->gic_irqs = gic_irqs;
> >>
> >> -	if (node) {		/* DT case */
> >> +	if (node || !acpi_disabled) {		/* DT or ACPI case */
> >>   		gic->domain = irq_domain_add_linear(node, gic_irqs,
> >>   						    &gic_irq_domain_hierarchy_ops,
> >>   						    gic);

I think this is a bit more worrying, I mean passing a NULL node pointer to
the irqdomain layer which basically means you are booting out of ACPI
(for you, if that's true for the irq_domain_add_linear implementation
that's another story), the node pointer should be optional but you
need feedback from IRQ layer maintainers here.

Lorenzo
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