From: David Daney <ddaney@caviumnetworks.com>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org
Subject: Re: [PATCH] MIPS: Add some irq definitins required by OF
Date: Tue, 26 Oct 2010 15:18:38 -0700 [thread overview]
Message-ID: <4CC753BE.5010705@caviumnetworks.com> (raw)
In-Reply-To: <AANLkTi=M0Fk5EGy+JB2CZcGxspv3hPde10A-R5sUs3Jq@mail.gmail.com>
On 10/14/2010 06:27 PM, Grant Likely wrote:
> On Thu, Oct 14, 2010 at 3:02 PM, David Daney<ddaney@caviumnetworks.com> wrote:
[...]
>>
>> +#define NO_IRQ UINT_MAX
>
> Really? The verdict came down a long time ago that 0 is to be the
> value that means no irq, and only a few architectures still define
> NO_IRQ as -1. It is assumed that the architectures which do not
> define NO_IRQ use 0 as the invalid value. Mostly notably x86 does not
> define NO_IRQ, and Linus nack'd the patch to add it.
>
I was not part of that discussion.
I would however note, that all the irq functions return unsigned, so a
value of -1 is meaningless. Also my understanding is that 8259 based
systems use the values of 0 - 15 as the interrupt numbers, making 0
unavailable for use as NO_IRQ.
Given these constraints, UINT_MAX would seem to be a good value. It has
to be defined as something *and* have global visibility, because it is
part of the OF irq mapping functions API.
David Daney
next prev parent reply other threads:[~2010-10-26 22:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-14 21:02 [PATCH] MIPS: Add some irq definitins required by OF David Daney
2010-10-15 1:27 ` Grant Likely
2010-10-15 19:50 ` David Daney
2010-10-15 19:55 ` Grant Likely
2010-10-26 22:18 ` David Daney [this message]
2010-10-27 8:10 ` Grant Likely
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