On Wednesday, October 08, 2014 11:55:08 AM Alexandre Courbot wrote: > On Wed, Oct 8, 2014 at 9:09 AM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > > On Tuesday, October 07, 2014 07:52:02 PM Alexandre Courbot wrote: > >> 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. > > > > I'm wondering if that can be done after merging the current work? > > > > We'll be able to use the drivers in question with our hardware in the > > meantime then ... > > Yeah, that's probably ok. The properties in question already exist so > we will have to support them anyway ; it's just a matter of seeing > whether we can improve the proposed way. > > So for now: > > Acked-by: Alexandre Courbot <acourbot@xxxxxxxxxx> Thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
