Messages in this thread |  | | Subject | Re: [PATCH 1/2] staging: iio: ad7606: replace range/range_available with corresponding scale | From | Jonathan Cameron <> | Date | Sat, 19 Nov 2016 12:32:42 +0000 |
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On 14/11/16 23:12, Linus Walleij wrote: > On Mon, Nov 14, 2016 at 7:53 PM, Lars-Peter Clausen <lars@metafoo.de> wrote: > >> It's about figuring out the setting of a "GPIO" that can't be changed from >> software. >> >> Devices sometimes, instead of a configuration bus like I2C or SPI, use >> simple input pins, that can either be set to high or low, to allow software >> the state of the device. The GPIO API is typically used to configure these pins. >> >> This works fine as long as the pin is connected to a GPIO. But sometimes the >> system designer decides that a settings does not need to be configurable, in >> this case the pin will be tied to logic low or high directly on the PCB >> without any GPIO controller being involved. >> >> Sometimes a driver wants to know how the pin is wired up so it can report to >> userspace this part runs in the following mode and the mode can't be >> changed. In a sense it is like a reverse GPIO hog. >> >> Considering that this is a common usecase the question was how this can be >> implemented in a driver independent way to avoid code duplication and >> slightly different variations of what is effectively the same DT/ACPI binding. >> >> E.g. lets say for a configurable pin you use >> >> range-gpio = <&gpio ...>; >> >> and for a static pin >> >> range-gpio-fixed = <1>; >> >> Or something similar. > > Aha I understand. > > Usually I feel we need not shoehorn stuff into GPIO because it is convenient, > it might be best to leave the GPIO optional and if it is not there, look for > a custom attribute that represents the "hogging" to 0/1. I think trying > to extend GPIO bindings to cover it is overgeneralization, instead go > for a local binding for this kind of devices. > > But mainly it is a question to the DT bindings maintainers. That's a reasonable approach, but I'd certainly like to see a generic binding to describe it. It's a pretty common situation.
Seems more likely we'll get a device tree maintainer response if we cc them ;)
So Mark, Rob and thoughts on this?
Thanks,
Jonathan > > Yours, > Linus Walleij >
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