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SubjectRe: [PATCH 1/2] rtc: rtc-ds1374: fix 'no irq' case handling
On Tue, Aug 19, 2008 at 04:39:09PM -0400, Jon Smirl wrote:
> On 8/12/08, Anton Vorontsov <avorontsov@ru.mvista.com> wrote:
> > On a PowerPC board with ds1374 RTC I'm getting this error while
> > RTC tries to probe:
> >
> > rtc-ds1374 0-0068: unable to request IRQ
> >
> > This happens because I2C probing code (drivers/of/of_i2c.c) is
> > specifying IRQ0 for 'no irq' case, which is correct.
>
> Shouldn't this be
>
> > - if (client->irq <= NO_IRQ)
>
> instead of
>
> > - if (client->irq < 0)
> > + if (client->irq <= 0)
>
> Since NO_IRQ can vary by platform (0 or -1)?

First of all, NO_IRQ is not defined for every architecture. You can't
use it for truly cross-platform drivers.

Secondly, "<= 0" will work for both NO_IRQ == 0 and NO_IRQ == -1,
since client->irq is signed type.

As for false positives, I don't believe that there is any platform
that use IRQ0 for external interrupts.

[...]
> In of_i2c.c shouldn't there be an error check?
>
> info.irq = irq_of_parse_and_map(node, 0);
>
> if (info.irq < NO_IRQ) {report error; continue }

irq_of_parse_and_map() returns unsigned type, plus it is defined
only for PowerPC, and for PowerPC NO_IRQ is always 0.

--
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2


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