Re: [PATCH 6/8] regulator: max77686: Add external GPIO control

From: Krzysztof Kozlowski
Date: Wed Oct 29 2014 - 06:42:53 EST


On wto, 2014-10-28 at 13:11 +0100, Krzysztof Kozlowski wrote:
> On wto, 2014-10-28 at 09:52 +0100, Krzysztof Kozlowski wrote:
> > On pon, 2014-10-27 at 21:03 +0100, Javier Martinez Canillas wrote:
> > > Hello Krzysztof,
> > >
> > > On 10/27/2014 04:03 PM, Krzysztof Kozlowski wrote:
> > > > @@ -85,6 +91,9 @@ struct max77686_data {
> > > > struct max77686_regulator_data *regulators;
> > > > int num_regulators;
> > > >
> > > > + /* Array of size num_regulators with GPIOs for external control. */
> > > > + int *ext_control_gpio;
> > > > +
> > >
> > > The integer-based GPIO API is deprecated in favor of the descriptor-based GPIO
> > > interface (Documentation/gpio/consumer.txt). Could you please use the later?
> >
> > Sure, I can. Please have in mind that regulator core still accepts old
> > GPIO so I will have to use desc_to_gpio(). That should work... and
> > should be future-ready.
>
> It seems I was too hasty... I think usage of the new gpiod API implies
> completely different bindings.
>
> The gpiod_get() gets GPIO from a device level, not from given sub-node
> pointer. This means that you cannot have DTS like this:
> ldo21_reg: ldo21 {
> regulator-compatible = "LDO21";
> regulator-name = "VTF_2.8V";
> regulator-min-microvolt = <2800000>;
> regulator-max-microvolt = <2800000>;
> ec-gpio = <&gpy2 0 0>;
> };
>
> ldo22_reg: ldo22 {
> regulator-compatible = "LDO22";
> regulator-name = "VMEM_VDD_2.8V";
> regulator-min-microvolt = <2800000>;
> regulator-max-microvolt = <2800000>;
> ec-gpio = <&gpk0 2 0>;
> };
>
>
> I could put GPIOs in device node:
>
> max77686_pmic@09 {
> compatible = "maxim,max77686";
> interrupt-parent = <&gpx0>;
> interrupts = <7 0>;
> reg = <0x09>;
> #clock-cells = <1>;
> ldo21-gpio = <&gpy2 0 0>;
> ldo22-gpio = <&gpk0 2 0>;
>
> ldo21_reg: ldo21 {
> regulator-compatible = "LDO21";
> regulator-name = "VTF_2.8V";
> regulator-min-microvolt = <2800000>;
> regulator-max-microvolt = <2800000>;
> };
>
> ldo22_reg: ldo22 {
> regulator-compatible = "LDO22";
> regulator-name = "VMEM_VDD_2.8V";
> regulator-min-microvolt = <2800000>;
> regulator-max-microvolt = <2800000>;
> };
>
> This would work but I don't like it. The properties of a regulator are
> above the node configuring that regulator.
>
> Any ideas?
>

Continuing talking to myself... I found another problem - GPIO cannot be
requested more than once (-EBUSY). In case of this driver (and board:
Trats2) one GPIO is connected to regulators. The legacy GPIO API and
regulator core handle this.

With new GPIO API I would have to implement some additional steps in
such case...

So there are 2 issues:
1. Cannot put GPIO property in regulator node.
2. Cannot request some GPIO more than once.

I'm going back to legacy API for now.

Best regards,
Krzysztof

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