On Tue, Oct 7, 2014 at 7:40 PM, Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > On Tue, Oct 07, 2014 at 07:22:13PM +0900, Alexandre Courbot wrote: >> On Tue, Oct 7, 2014 at 9:18 AM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: >> > From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> >> > >> > Some drivers need to deal with only firmware representation of its >> > GPIOs. An example would be a GPIO button array driver where each button >> > is described as a separate firmware node in device tree. Typically these >> > child nodes do not have physical representation in the Linux device >> > model. >> > >> > In order to help device drivers to handle such firmware child nodes we >> > add dev[m]_get_named_gpiod_from_child() that takes a child firmware >> > node pointer as its second argument (the first one is the parent device >> > itself), finds the GPIO using whatever is the underlying firmware >> > method, and requests the GPIO properly. >> > >> > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> >> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> >> >> ... >> >> > +/* Child properties interface */ >> > +struct gpio_desc *dev_get_named_gpiod_from_child(struct device *dev, void *child, >> > + const char *propname, int index); >> > +struct gpio_desc *devm_get_named_gpiod_from_child(struct device *dev, void *child, >> > + const char *propname, int index); >> >> I see the reason for these functions and am not opposed to them. >> However, I wonder if we could not replace propname by a con_id that >> would be resolved to one of con_id-gpio for DT and whatever naming >> convention ACPI is using? > > The code in gpio-leds.c and gpio_keys_polled.c refers to "gpios" as the > property name. If we can change that somehow to work with con_id-gpio > instead without breaking things, then why not. > >> This would prevent users to name GPIOs outside of the conventions >> defined in the bindings and be generally safer. Is there a particular >> reason (used by some old code?) for the current direct property >> access? If not, maybe we could call a slightly-modified of_find_gpio() >> to resolve the GPIO property for DT, and the equivalent function for >> ACPI? > > Only reason I can think of is support for the existing properties that > are used directly. Drivers using gpiod_get() and friends do not need > dev_get_named_gpiod_from_child() anyway. Right. Another thing is that the property handling code (active low only for now) is duplicated again, but that can be addressed separately. I will have a look at gpio-leds and gpio_keys_polled to see if we cannot make this work at a higher level. It's easier to have the bindings respected if the code itself enforces them. -- 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
