linux-kernel - Re: [PATCH v3] of/irq: Get rid of NO

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Date:	Tue, 06 Dec 2011 21:51:14 -0600
From:	Rob Herring <robherring2@...il.com>
To:	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Ingo Molnar <mingo@...e.hu>, Jeff Garzik <jgarzik@...hat.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	devicetree-discuss@...ts.ozlabs.org,
	LKML <linux-kernel@...r.kernel.org>, linux-ide@...r.kernel.org,
	Randy Dunlap <rdunlap@...otime.net>,
	linux-next@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Michal Simek <monstr@...str.eu>,
	John Linn <John.Linn@...inx.com>
Subject: Re: [PATCH v3] of/irq: Get rid of NO_IRQ usage

On 12/06/2011 05:16 PM, 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 <anton.vorontsov@...aro.org>
> ---

Looks fine, but I think we have to wait for microblaze to be fixed or
some confirmation from microblaze folks that no driver would use IRQ0.
There was a patch posted by Grant in back in Feb, but nothing has
happened since:

http://article.gmane.org/gmane.linux.uclinux.microblaze/10121/

Rob

> 
> On Tue, Dec 06, 2011 at 01:25:07PM -0800, Linus Torvalds wrote:
>> On Tue, Dec 6, 2011 at 1:22 PM, Rob Herring <robherring2@...il.com> wrote:
>>>
>>> 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.
>>
>> I do agree. Especially since we never got any input on whether it works or not.
>>
>>> If not, you don't need to handle irq_create_of_mapping return as that is
>>> already always 0 for no irq or error.
>>
>> Yeah, I'd like to just remove NO_IRQ from the OF paths. Afaik, it
>> hasn't worked as NO_IRQ before anyway, so even if the rest of the
>> drivers end up continuing using NO_IRQ, the OF-enabled ones on ARM
>> should just stop. There can't be many of those yet.
> 
> Okay, here it goes.
> 
>  drivers/of/irq.c |   13 ++++---------
>  1 files changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index 791270b..ac6da0d 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
> @@ -44,7 +39,7 @@ unsigned int irq_of_parse_and_map(struct device_node *dev, int index)
>  	struct of_irq oirq;
>  
>  	if (of_irq_map_one(dev, index, &oirq))
> -		return NO_IRQ;
> +		return 0;
>  
>  	return irq_create_of_mapping(oirq.controller, oirq.specifier,
>  				     oirq.size);
> @@ -345,7 +340,7 @@ 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 +358,7 @@ 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 +378,7 @@ 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;

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