Re: [PATCH 1/3] staging:iio:magnetometer:ak8975 Don't use irq_to_gpio()

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Thursday 01 September 2011, Stephen Warren wrote:
> One question: When we add this field, how do drivers tell whether a value
> of 0 is an uninitialized field, or a legitimate GPIO value of 0? Should we
> add a flag to indicate validity, or just work hard to not enable driver-
> side code to use this value until we've fixed up all places that instantiate
> the driver to initialize the field to some invalid value like -1?

I think it's enough to coordinate the driver with the initialization of the
i2c data. If a driver requires a GPIO number, it can assume that it's valid.
Drivers that don't need one don't care. If it's an optional feature, you
might want to either use platform_data after all, or use different identifiers
for devices that have a gpio vs. those that have none -- in effect those are
different types of devices handled by the same driver.

	Arnd