Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 1/3] staging:iio:magnetometer:ak8975 Don't use irq_to_gpio() | Date | Thu, 1 Sep 2011 18:20:25 +0200 |
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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
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