Re: [PATCH 1/2] net: ll_temac: fix interrupt bug when interrupt 0 is used

[Grant Likely <grant.likely@secretlab.ca>]

On Sun, Jun 6, 2010 at 3:57 PM, Benjamin Herrenschmidt
<benh@kernel.crashing.org> wrote:
> On Wed, 2010-05-26 at 11:29 -0600, John Linn wrote:
>> The code is not checking the interrupt for DMA correctly so that an
>> interrupt number of 0 will cause a false error.
>>
>> Signed-off-by: Brian Hill <brian.hill@xilinx.com>
>> Signed-off-by: John Linn <john.linn@xilinx.com>
>> ---
>>  drivers/net/ll_temac_main.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/net/ll_temac_main.c b/drivers/net/ll_temac_main.c
>> index fa7620e..0615737 100644
>> --- a/drivers/net/ll_temac_main.c
>> +++ b/drivers/net/ll_temac_main.c
>> @@ -950,7 +950,7 @@ temac_of_probe(struct of_device *op, const struct of_device_id *match)
>>
>>       lp->rx_irq = irq_of_parse_and_map(np, 0);
>>       lp->tx_irq = irq_of_parse_and_map(np, 1);
>> -     if (!lp->rx_irq || !lp->tx_irq) {
>> +     if ((lp->rx_irq == NO_IRQ) || (lp->tx_irq == NO_IRQ)) {
>>               dev_err(&op->dev, "could not determine irqs\n");
>>               rc = -ENOMEM;
>>               goto nodev;
>
> Hasn't NO_IRQ been deprecated ?

ARM still uses it, plus less than a handful of other arches.  There is
no reason for Microblaze to use NO_IRQ as -1.

In fact, on ARM, as part of the device tree work I'm hoping to piggy
back in irq remapping and make 0 no longer a valid irq.

> Linus made it clear a while back that interrupt 0 was not valid and
> that's the way it should be.
>
> We now have an interrupt remapping scheme on powerpc, so we ensure that
> 0 always mean no interrupt. Other archs might need some fixups. Which
> are specifically needs this patch ?

Microblaze.

BTW jlinn, for xilinx ARM support we should make sure 0 is never used
as a valid IRQ from day one.  It will result it far less pain in the
future.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.