On Sun, Jul 28, 2013 at 6:45 PM, Alexander Holler <[email protected]> wrote:
> Am 28.07.2013 18:25, schrieb Linus Walleij:
>> On Sun, Jul 28, 2013 at 4:25 PM, Alexander Holler <[email protected]>
>> wrote:
>>
>>> By the way, if someone decides to touch omap_hsmmc, the driver wrongly
>>> assumes that 0 is not a valid IRQ number and it doesn't check if
>>> gpio_to_irq() returns a negative value. ;)
>>
>> Zero *is* *not* a valid IRQ number.
>
> Where is that mentioned?
>
> gpio.txt states:
>
> ----
> Non-error values returned from gpio_to_irq() can be passed to request_irq()
> or free_irq(). They will often be stored into IRQ resources for platform
> ----
>
> With the new patches gpio_to_irq() returns 0.
>
Hi Alexander,
gpio_to_irq() returns 0 because omap_gpio_to_irq() calls
irq_find_mapping() and this does:
if (domain == NULL)
return 0;
So gpio_to_irq() returning zero means that there isn't a GPIO-IRQ
mapping domain not that the 0 is the virtual IRQ number mapped to this
GPIO.
> Documentation/IRQ-domain.txt:
> ----
> The legacy map should only be used if fixed IRQ mappings must be
> supported. For example, ISA controllers would use the legacy map for
> mapping Linux IRQs 0-15 so that existing ISA drivers get the correct IRQ
> numbers.
> ----
>
> You see the 0 too?
>
> And while browsing some other source I had the impression zero might be
> a valid irq number too, at least in regard to the IRQ apis. If it's a
> valid IRQ nuber on ARM is something else.
>
> Of ourse, I might be wrong, but you just stated that 0 isn't valid, and
> I would be happy to find a source for your statement.
>
> Alexander Holler
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