Re: [PATCH v3] can/sja1000: add support for PEAK-System PCMCIA card

[Oliver Hartkopp <socketcan@hartkopp.net>]

>> I would also have say that before, but I checked that IRQ_NONE may be
>> processed as spurious, so I don't even know, for the moment. LDD3
>> chapter 10 also says:
>>
>>> Interrupt handlers should return a value indicating whether there was
>>> actually an
>>> interrupt to handle. If the handler found that its device did, indeed,
>>> need attention, it
>>> should return IRQ_HANDLED; otherwise the return value should be IRQ_NONE.
>>
>> So, what does this "need attention" stands for? Since the device is
>> unplugged, we could say that it didn't need any attention anymore...
>> But, on the other hand, the ems_pcmcia driver does return IRQ_HANDLED
>> when its private check fails to detect the card and it has been
>> approved, so, where is the truth? Near the perfection? ;-)
> 
> From http://lxr.linux.no/#linux+v3.2.6/include/linux/irqreturn.h:
> 
>   IRQ_NONE            interrupt was not from this device


See:

http://lxr.linux.no/#linux+v3.2.6/kernel/irq/spurious.c#L178

I think at plug-out we get very little IRQ_NONE return values that should be
ok not to damage the entire handling of that specific irq line ...

Regards,
Oliver