On Fri, Aug 10, 2012 at 10:19:02AM +0200, Linus Walleij wrote: > On Thu, Aug 9, 2012 at 10:20 PM, Thierry Reding > <thierry.red...@avionic-design.de> wrote: > > On Sun, Jul 29, 2012 at 07:13:57PM +0200, Linus Walleij wrote: > >> > + client->irq = irq_of_parse_and_map(client->dev.of_node, 0); > >> > + if (client->irq == NO_IRQ) > >> > >> Just if (!client->irq) since NO_IRQ is 0 nowadays. > > > > At the risk of seeming pedantic, NO_IRQ is in fact quite often not 0. > > No. A year back, yes, but not anymore. We went to great lengths in the > ARM architecture to ensure NO_IRQ is *always 0. Russell spent > a lot of time on this. > > Consult the following article on LWN: > http://lwn.net/Articles/470820/ > > Then grep your gitlog and you'll see we got rid of it from ARM.
Then why is there still the following in arch/arm/include/asm/irq.h?
/*
* Use this value to indicate lack of interrupt
* capability
*/
#ifndef NO_IRQ
#define NO_IRQ ((unsigned int)(-1))
#endif
> If this driver is for some other arch like openrisc I might accept
> it but please reconsider.
There's nothing in the driver that makes it ARM specific, so it could be
used on other platforms just as well. But as I also said in my previous
mail, in this particular case the value for the interrupt comes from the
call to irq_of_parse_and_map(), which will return 0 on failure,
regardless of the architecture, so there is actually no problem.
Thierry
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