On Tue, Oct 21, 2014 at 4:54 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Tuesday 21 October 2014 14:14:02 Alexandre Courbot wrote: >> > >> > We have enforced naming things for the dmaengine binding, which has >> > just led to everyone calling things "rx" and "tx". My fear is that >> > if we start to enforce giving a name, we'd end up with lots of >> > drivers that use a "gpio-gpios" property or something silly. >> >> Checking the bindings is also part of the review process. Things >> like "gpio-gpios" should simply not be accepted to begin with. >> >> This sounds like a good chance to finally land some guidelines >> regarding GPIO bindings. Let's summarize the situation: >> - GPIO bindings can be defined using both DT and ACPI (both interfaces >> nicely abstracted by the interface introduced by this series) >> - Both firmware interfaces support indexed GPIOs >> - Both firmware interfaces support named GPIO properties, with an >> optional index (can we absolutely take this for granted on ACPI now?) > > The developers working on it have said that they definitely want to > be compatible with the existing bindings, so the answer to your question > is yes. > >> - For DT bindings, both foo-gpio and foo-gpios are valid properties >> for the GPIO "foo". > > I would like to see the documentation recommend one over the other for > new bindings. Most other subsystems use the plural form even for > properties that only have one entry, so I'd like to see "foo-gpios" > become the canonical form for named gpio lines. Sounds good. > Drivers that use > existing bindings with the "foo-gpio" form (or worse, "foo-somethingelse" > can use the same internal interface as the drivers that use name plus > index. Do you see a problem using what I suggested for the combined > API: > > __gpiod_get(dev, propname, index); // use property name plus index > gpiod_get(dev, index); // use "gpios" plus index > gpiod_get_named(dev, "name"); use "name-gpios" with index 0 Apart from the loosy naming practices which we sometimes see (and which should be caught during review), do you have something against requiring a name for all new GPIO bindings, i.e. for ensuring that all new properties are "name-gpio" and forbidding "gpios"? Requiring a proper name for all GPIOs makes a lot of sense IMHO, it makes drivers easier to understand and is less error-prone than long arrays of GPIOs. The API would then be basically what we have today: gpiod_get(dev, name) // use "name-gpios" with index 0 gpiod_get_index(dev, name, index) // for the rare case where several GPIOs serve the same function. Not to be used lightly. ... with stronger guidelines for the definition of new bindings, and a big warning in the kerneldoc of gpiod_get_index(). ACPI drivers that may use tables without _DSD should then use a way to bind GPIO names to indexes as a fallback for older hardware. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
