[[RFC PATCH]] gpio: gpio-mxc: make sure gpio is input when request IRQ

[Linus Walleij]

On Fri, Jul 25, 2014 at 2:52 PM, Markus Niebel
<list-09_linux_arm at tqsc.de> wrote:
> Am 25.07.2014 13:38, wrote Linus Walleij:

>> I don't know if it'd be a good idea to loop over all gpios in a new
>> irqchip and fetch the direction just to get the flags right, so far
>> we haven't done that and I don't know what the usecase would be.
>
> I've came to a situation where it would have been helpful to know - bootloader
> configured a pin as output and linux tried to configure the pin as IRQ input.
> *YES I KNOW THIS IS NOT CORRECT* but it took some time to see, what happened.

Hm, maybe we should call gpiod_get_direction() first in
gpio_lock_as_irq(), so we check the hardware and know there that the
flag is correctly set here?

>> If we need that we should do it in gpiolib for all drivers don't you
>> think?
>
> A pragmatic / lean solution would be to deny the IRQ configuration when
> seeing the pin configured as output in hardware and print out an error
> on the gpio driver level.

I guess that is what I'm suggesting, not sure if I follow
correctly.

Yours,
Linus Walleij