Ben Dooks wrote: > On Mon, Aug 11, 2008 at 07:19:13PM +0400, Anton Vorontsov wrote: > >> When no irq specified, pata_of_platform fills irq_res with -1, >> which is wrong to do for two reasons: >> >> 1. By definition, 'no irq' should be IRQ 0, not some negative integer; >> > > interesting, IRQ 0 is actually valid on some ARM systems. > >
It is here too, but I believe most of the code uses a virtualized irq number, so physical IRQ 0 would presumably get mapped to a non-zero virtual one. >> 2. pata_platform checks for irq_res.start > 0, but since irq_res.start >> is unsigned type, the check will be true for `-1'. >> >> Reported-by: Steven A. Falco <[EMAIL PROTECTED]> >> Signed-off-by: Anton Vorontsov <[EMAIL PROTECTED]> >> --- >> >> On Mon, Aug 11, 2008 at 10:48:50AM -0400, Steven A. Falco wrote: >> >>> I think there is a bug in the communications between pata_of_platform >>> and pata_platform. I will refer to the master branch of the DENX git >>> tree, which is roughly v2.6.26.1 at this time. I am using a Sequoia >>> board with a PPC440EPx. >>> >>> In pata_of_platform, we have: >>> >>> ret = of_irq_to_resource(dn, 0, &irq_res); >>> if (ret == NO_IRQ) >>> irq_res.start = irq_res.end = -1; >>> >>> so if there is no interrupt defined, then start and end are -1. >>> However, __pata_platform_probe has: >>> >>> if (irq_res && irq_res->start > 0) { >>> irq = irq_res->start; >>> irq_flags = irq_res->flags; >>> } >>> >>> You might think that the (irq_res->start > 0) test will fail, as it >>> should in this no-irq case. But, start is a u64, so the -1 actually >>> looks like a large positive number in the comparison. So, >>> __pata_platform_probe attempts to use an interrupt when there isn't one. >>> >>> I think the fix would be to change __pata_platform_probe to: >>> >>> if (irq_res && irq_res->start != -1) { >>> >>> but that might have other unintended consequences, so I'll defer to >>> whomever knows more about the intent of this code. >>> >> Something like this patch should work. Thanks for noticing! >> >> 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 408da30..1f18ad9 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 >> of_device *ofdev, >> >> ret = of_irq_to_resource(dn, 0, &irq_res); >> if (ret == NO_IRQ) >> - irq_res.start = irq_res.end = -1; >> + irq_res.start = irq_res.end = 0; >> else >> irq_res.flags = 0; >> >> > >
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