Subject: Re: [PATCH 1/2] of/irq: Get rid of NO_IRQ usage

From: Rob Herring <[email-masked]>
Date: Tue, 06 Dec 2011 15:22:02 -0600

On 11/10/2011 09:25 AM, Anton Vorontsov wrote:
> PPC32/64 defines NO_IRQ to zero, so no problems expected.
> ARM defines NO_IRQ to -1, but OF code relies on IRQ domains support,
> which returns correct ('0') value in 'no irq' case. So everything
> should be fine.
> 
> Other arches might break if some of their OF drivers rely on NO_IRQ
> being not 0. If so, the drivers must be fixed, finally.
> 
> Signed-off-by: Anton Vorontsov <[email-masked]>
> ---
>  drivers/of/irq.c |   30 ++++++++++++++++++------------
>  1 files changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index 6d3dd39..2dd4937 100644
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -26,11 +26,6 @@
>  #include <linux/string.h>
>  #include <linux/slab.h>
>  
> -/* For archs that don't support NO_IRQ (such as x86), provide a dummy value */
> -#ifndef NO_IRQ
> -#define NO_IRQ 0
> -#endif
> -
>  /**
>   * irq_of_parse_and_map - Parse and map an interrupt into linux virq space
>   * @device: Device node of the device whose interrupt is to be mapped
> @@ -42,12 +37,23 @@
>  unsigned int irq_of_parse_and_map(struct device_node *dev, int index)
>  {
>  	struct of_irq oirq;
> +	int ret = 0;
>  
>  	if (of_irq_map_one(dev, index, &oirq))
> -		return NO_IRQ;
> -
> -	return irq_create_of_mapping(oirq.controller, oirq.specifier,
> -				     oirq.size);
> +		goto no_irq;
> +
> +	ret = irq_create_of_mapping(oirq.controller, oirq.specifier,
> +				    oirq.size);
> +no_irq:
> +#ifdef NO_IRQ
> +#if NO_IRQ != 0
> +	if (ret == NO_IRQ)
> +		pr_warn("Hit NO_IRQ case for your arch. Drivers might expect "
> +			"NO_IRQ, but we return 0. If anything breaks, driver "
> +			"have to be fixed.\n");
> +#endif
> +#endif

This warning code is really ugly. Can we just drop it? In my searching
of in kernel dts files, there's only 1 instance I have found (Versatile
AB watchdog) that would hit this.

If not, you don't need to handle irq_create_of_mapping return as that is
already always 0 for no irq or error.

Otherwise, looks fine.

Rob

> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(irq_of_parse_and_map);
>  
> @@ -345,7 +351,7 @@ int of_irq_to_resource(struct device_node *dev, int index, struct resource *r)
>  
>  	/* Only dereference the resource if both the
>  	 * resource and the irq are valid. */
> -	if (r && irq != NO_IRQ) {
> +	if (r && irq) {
>  		r->start = r->end = irq;
>  		r->flags = IORESOURCE_IRQ;
>  		r->name = dev->full_name;
> @@ -363,7 +369,7 @@ int of_irq_count(struct device_node *dev)
>  {
>  	int nr = 0;
>  
> -	while (of_irq_to_resource(dev, nr, NULL) != NO_IRQ)
> +	while (of_irq_to_resource(dev, nr, NULL))
>  		nr++;
>  
>  	return nr;
> @@ -383,7 +389,7 @@ int of_irq_to_resource_table(struct device_node *dev, struct resource *res,
>  	int i;
>  
>  	for (i = 0; i < nr_irqs; i++, res++)
> -		if (of_irq_to_resource(dev, i, res) == NO_IRQ)
> +		if (!of_irq_to_resource(dev, i, res))
>  			break;
>  
>  	return i;