On Tue, Dec 05, 2017 at 09:00:37PM +0800, Chen-Yu Tsai wrote: > On Tue, Dec 5, 2017 at 6:05 PM, Maxime Ripard > <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote: > > Hi, > > > > On Sat, Dec 02, 2017 at 12:27:33AM +0800, Chen-Yu Tsai wrote: > >> The Bananapi-M64 has 3 LEDS in red, green, and blue. These are toggled > >> via GPIO lines, which drive transistors that control current across the > >> LEDS. The red LED is by default on, via an additional pull-up on the > >> control line. We consider this means that it is a power indicator. > >> So we set the "default-on" property for it. > >> > >> The pingroups the GPIO lines belong to require external regulators be > >> enabled to be able to drive the GPIO high. These regulators also have > >> other purposes. However the pin controller does not have bindings for > >> regulators. Here we just set them to always-on. > > > > I guess we should take the opportunity to do just that. > > > > We have been deferring this for quite some time now, this is a perfect > > occasion to do it once and for all :) > > True. But right now I don't see an elegant solution. What is the purpose > of having the regulator tied to pinctrl / GPIO? You can't have the pinctrl > driver asking for the regulator at probe time, as it might not be available > or even have a cyclic dependency (because the PMIC is I2C driven, which > needs an I2C controller, which needs the pinctrl). Ah, right, you definitely have a circular dependency. > If you defer fetching the regulator to a later point, you might end > up with an inconsistent state. Again with the I2C driven regulator > example, what happens if the regulator core decides to turn the > regulator off before the pinctrl side has a chance to take a > reference and enable it? I guess you could implement something based on the an asynchronous regulator_get. You call regulator_get_async (or whatever) in the pinctrl probe, and get notified as soon as it is registered so that you can act upon it. Anyway, this is a bit too much to ask to enable 3 LEDs... I've applied that patch. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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