linux-kernel - Re: [PATCH v4 2/2] irqchip: add J-Core AIC driver

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Message-ID: <20160727101235.GC12880@leverpostej>
Date:	Wed, 27 Jul 2016 11:12:36 +0100
From:	Mark Rutland <mark.rutland@....com>
To:	Rich Felker <dalias@...c.org>
Cc:	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org,
	devicetree@...r.kernel.org, Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v4 2/2] irqchip: add J-Core AIC driver

On Wed, Jul 27, 2016 at 05:35:09AM +0000, Rich Felker wrote:
> +int __init aic_irq_of_init(struct device_node *node, struct device_node *parent)
> +{
> +	struct aic_data *aic = &aic_data;
> +	unsigned min_irq = 64;
> +
> +	pr_info("Initializing J-Core AIC\n");
> +
> +	if (!of_device_is_compatible(node, "jcore,aic2")) {
> +		unsigned cpu;
> +		for_each_possible_cpu(cpu) {
> +			void __iomem *base = of_iomap(node, cpu);
> +			if (!base)
> +				continue;

This sounds like it would be a critical error.

It would be best to at least pr_warn() if you can't map a CPU's AI
interface.

> +			pr_info("Local AIC1 enable for cpu %u at %p\n",
> +				cpu, base + AIC1_INTPRI);
> +			__raw_writel(0xffffffff, base + AIC1_INTPRI);
> +		}

Here base goes out of scope. If you don't need it, it would be best
practice to iounmap it (even if that happens to be a no-op on your
arch).

> +		min_irq = 16;
> +	}
> +
> +	aic->chip.name = node->name;

It's probably best to give the name explicitly in the driver (e.g.
"AIC"), rather than taknig whatever happens to be in the DT (which
should be 'interrupt-controller@<addr>'.

> +	aic->chip.irq_mask = noop;
> +	aic->chip.irq_unmask = noop;

If the core code wants to mask IRQs, how do you handle that? Can you
mask your CPU traps?

Thanks,
Mark.