Re: [PATCH] ata: Don't use NO_IRQ in pata_of_platform driver

From: Dave Martin <dave.martin@linaro.org>
To: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Andrew Morton <akpm@linux-foundation.org>,
	devicetree-discuss@lists.ozlabs.org,
	LKML <linux-kernel@vger.kernel.org>,
	linux-ide@vger.kernel.org, Randy Dunlap <rdunlap@xenotime.net>,
	linux-next@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jeff Garzik <jgarzik@redhat.com>, Pawel Moll <pawel.moll@arm.com>,
	linux-arm-kernel@localhost.localdomain
Subject: Re: [PATCH] ata: Don't use NO_IRQ in pata_of_platform driver
Date: Fri, 2 Dec 2011 19:26:18 +0000	[thread overview]
Message-ID: <20111202192618.GC3037@localhost.localdomain> (raw)
In-Reply-To: <20111110162859.GA7088@oksana.dev.rtsoft.ru>

[expanding CC -- apologies to anyone who gets this mail twice]

On Thu, Nov 10, 2011 at 08:28:59PM +0400, Anton Vorontsov wrote:
> Drivers should not use NO_IRQ; moreover, some architectures don't
> have it nowadays. '0' is the 'no irq' case.
> 
> Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
> Acked-by: Alan Cox <alan@linux.intel.com>
> ---
> 
> On Thu, Nov 10, 2011 at 03:38:16PM +0000, Alan Cox wrote:
> > On Thu, 10 Nov 2011 19:26:06 +0400
> > Anton Vorontsov <cbouatmailru@gmail.com> wrote:
> > 
> > > Drivers should not use NO_IRQ; moreover, some architectures don't
> > > have it nowadays. '0' is the 'no irq' case.
> > > 
> > > Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
> > 
> > Acked-by: Alan Cox <alan@linux.intel.com>
> 
> In case if we don't want a "band-aid fix" for 3.2, here is the patch
> that just does the proper fix (w/ a risk to break minor architectures).

This is now broken on ARM where, for good or bad, NO_IRQ currently is
used and is -1.

How do we resolve it?  If we are ready to eliminate NO_IRQ from
drivers/of/irq.c (or indeed, all code that uses it) and just use 0 for
that case, we should surely just do it... but I'm not confident I can
judge on that.

Half-removing NO_IRQ is going to be problematic, though...
I really don't care whether the "no irq" value is 0 or -1, but it is
abundantly clear that choosing different values to mean the same thing
on opposite sides of an interface does not work.

Cheers
---Dave

> 
>  drivers/ata/pata_of_platform.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/ata/pata_of_platform.c b/drivers/ata/pata_of_platform.c
> index a72ab0d..2a472c5 100644
> --- a/drivers/ata/pata_of_platform.c
> +++ b/drivers/ata/pata_of_platform.c
> @@ -52,7 +52,7 @@ static int __devinit pata_of_platform_probe(struct platform_device *ofdev)
>  	}
>  
>  	ret = of_irq_to_resource(dn, 0, &irq_res);
> -	if (ret == NO_IRQ)
> +	if (!ret)
>  		irq_res.start = irq_res.end = 0;
>  	else
>  		irq_res.flags = 0;
> -- 
> 1.7.5.3
> 
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