Re: [RFC 11/14] powerpc: Eliminate NO_IRQ usage

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Linux-Arch <linux-arch@vger.kernel.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Russell King <linux@arm.linux.org.uk>,
	linux-s390 <linux-s390@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Rob Herring <rob.herring@calxeda.com>,
	Linux-Next <linux-next@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [RFC 11/14] powerpc: Eliminate NO_IRQ usage
Date: Fri, 23 Aug 2013 15:22:51 +0200	[thread overview]
Message-ID: <CAMuHMdXtzwRY7VJe2EUssEPwGbFHwuHkwqbA+pi4N_Eujx3sNA@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdW0EE9MiwoOzvg_2VBf5QvYpgJ8bHsjV1HL8iN5HyhxYA@mail.gmail.com>

On Fri, Aug 23, 2013 at 3:18 PM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> On Fri, Jul 26, 2013 at 5:56 AM, Grant Likely <grant.likely@secretlab.ca> wrote:
>> On Thu, Jul 25, 2013 at 3:58 PM, Geert Uytterhoeven
>> <geert@linux-m68k.org> wrote:
>>> On Wed, Jan 11, 2012 at 9:22 PM, Grant Likely <grant.likely@secretlab.ca> wrote:
>>>> NO_IRQ is evil.  Stop using it in arch/powerpc and powerpc device drivers
>>>
>>>> diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c
>>>> index 3e06696..55c6ff9 100644
>>>> --- a/sound/soc/fsl/fsl_ssi.c
>>>> +++ b/sound/soc/fsl/fsl_ssi.c
>>>> @@ -666,7 +666,7 @@ static int __devinit fsl_ssi_probe(struct platform_device *pdev)
>>>>         ssi_private->ssi_phys = res.start;
>>>>
>>>>         ssi_private->irq = irq_of_parse_and_map(np, 0);
>>>> -       if (ssi_private->irq == NO_IRQ) {
>>>> +       if (!ssi_private->irq) {
>>>>                 dev_err(&pdev->dev, "no irq for node %s\n", np->full_name);
>>>>                 ret = -ENXIO;
>>>>                 goto error_iomap;
>>>
>>> What's the plan with this patch?
>>>
>>> This is now failing on xtensa, as it's one of the architectures that doesn't
>>> define NO_IRQ. Only arm, c6x, mn10300, openrisc, parisc, powerpc, and sparc
>>> define it.
>>
>> Wow. I'd pretty much dropped that patch because I didn't have time to
>> chase it down. It should be pursued though.
>>
>> In that particular case it is safe I think to apply the change. PPC
>> defines NO_IRQ to be 0 anyway.
>
> Note that we still have arches that define it as nonzero:
>
> arch/arm/include/asm/irq.h:#define NO_IRQ ((unsigned int)(-1))
> arch/mn10300/include/asm/irq.h:#define NO_IRQ INT_MAX
> arch/openrisc/include/asm/irq.h:#define NO_IRQ (-1)
> arch/parisc/include/asm/irq.h:#define NO_IRQ (-1)
> arch/sparc/include/asm/irq_32.h:#define NO_IRQ 0xffffffff
> arch/sparc/include/asm/irq_64.h:#define NO_IRQ 0xffffffff
>
> Only c6x and powerpc use zero, and thus are ready to drop NO_IRQ.

s390 just gained "NO_IRQ support" in -next, in commit
e15a9dcfdec29786d1830c5b7beaf02a288a89e1 ("s390: convert interrupt
handling to use generic hardirq"):

/* This number is used when no interrupt has been assigned */
#define NO_IRQ         0

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds