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;
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 <sfalco@xxxxxxxxxx>
Signed-off-by: Anton Vorontsov <avorontsov@xxxxxxxxxxxxx>
---
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;
--
1.5.6.3
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