Re: [PATCH v3 4/9] ARM: dts: sun7i: cubieboard2: add axp209 regulator nodes

[Maxime Ripard <maxime.ripard@free-electrons.com>]

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Hi,

On Mon, Jan 12, 2015 at 05:38:12PM +0800, Chen-Yu Tsai wrote:
> Hi,
> 
> On Mon, Jan 12, 2015 at 5:06 PM, Maxime Ripard
> <maxime.ripard@free-electrons.com> wrote:
> > Hi Chen-Yu,
> >
> > On Mon, Jan 12, 2015 at 12:34:04PM +0800, Chen-Yu Tsai wrote:
> >> This patch adds the regulator nodes for the axp209 by including
> >> the axp209 dtsi. As the inputs of these regulators are from the
> >> axp209's PS output, which is basically just a mux over the 2
> >> inputs, it is considered to be unregulated. Thus we do not provide
> >> input supply properties for them.
> >>
> >> The regulator names and constraints are based on the board
> >> schematics and the SoC datasheet.
> >>
> >> DCDC2 is used as the cpu power supply. This patch also references
> >> it from the cpu node.
> >>
> >> Also get rid of axp209 properties already set in axp209.dtsi.
> >>
> >> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> >> ---
> >>
> >> changes since v2
> >>
> >>     none
> >>
> >> changes since v1:
> >>
> >>     - Use preprocessor include for axp209.dtsi
> >>     - Remove incorrectly squashed axp209.dtsi patch
> >>
> >> ---
> >>  arch/arm/boot/dts/sun7i-a20-cubieboard2.dts | 35 +++++++++++++++++++++++++----
> >>  1 file changed, 31 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/arch/arm/boot/dts/sun7i-a20-cubieboard2.dts b/arch/arm/boot/dts/sun7i-a20-cubieboard2.dts
> >> index 18fc5db9c976..ec1fc2c8b3e3 100644
> >> --- a/arch/arm/boot/dts/sun7i-a20-cubieboard2.dts
> >> +++ b/arch/arm/boot/dts/sun7i-a20-cubieboard2.dts
> >> @@ -88,13 +88,9 @@
> >>                       status = "okay";
> >>
> >>                       axp209: pmic@34 {
> >> -                             compatible = "x-powers,axp209";
> >>                               reg = <0x34>;
> >>                               interrupt-parent = <&nmi_intc>;
> >>                               interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
> >> -
> >> -                             interrupt-controller;
> >> -                             #interrupt-cells = <1>;
> >>                       };
> >>               };
> >>
> >> @@ -145,3 +141,34 @@
> >>               status = "okay";
> >>       };
> >>  };
> >> +
> >> +#include "axp209.dtsi"
> >> +
> >> +&cpu0 {
> >> +     cpu-supply = <&reg_dcdc2>;
> >> +};
> >> +
> >> +&reg_dcdc2 {
> >> +     regulator-always-on;
> >> +     regulator-min-microvolt = <1000000>;
> >> +     regulator-max-microvolt = <1450000>;
> >> +     regulator-name = "vdd-cpu";
> >> +};
> >> +
> >> +&reg_dcdc3 {
> >> +     regulator-always-on;
> >> +     regulator-min-microvolt = <1000000>;
> >> +     regulator-max-microvolt = <1400000>;
> >> +     regulator-name = "vdd-int-dll";
> >> +};
> >> +
> >> +&reg_ldo1 {
> >> +     regulator-name = "vdd-rtc";
> >> +};
> >> +
> >> +&reg_ldo2 {
> >> +     regulator-always-on;
> >> +     regulator-min-microvolt = <3000000>;
> >> +     regulator-max-microvolt = <3000000>;
> >> +     regulator-name = "avcc";
> >> +};
> >
> > How do reg_vcc3v3 and the other reg used in this DT (ahci, USB) fit
> > into that?
> 
> The following applies to boards that use AXP209.
> 
> reg_vcc3v3 or reg_vcc3v0 is an external buck regulator with it's
> enable pin tied to EXTEN on the AXP. This pin is controllable,
> but we do not have the driver for it. It is possible that multiple
> regulators are tied to this pin. I suggest not touching it without
> the correct schematics.
> 
> The source for usb and ahci regulators, or reg_vcc5v if you will,
> is either the unregulated 5v from the power supply or the usb otg
> port. For the Cubietruck, there's an additional uncontrollable
> boost regulator that boosts the lipo battery's power up to 5v.
> 
> On some of the Olimex boards that use higher input voltages, they
> use an uncontrollable buck regulator to step down the voltage to
> 5v. The Olinuxino-Micro also has a boost regulator for the battery,
> tied to EXTEN.
> 
> The AXP209 simply does not have enough outputs for all the needed
> voltages.

Hmm, yes, ok. It makes sense.

> You could probably chain the regulators in the DT via xxx-supply
> if it helps. But beyond that, it is hard to do anything meaningful
> at this point. Modeling them as fixed regulators beyond our control
> is simpler. We also do not have an IPSOUT regulator for the AXP.
> 
> > Eventually, I think we would be able to remove
> > sunxi-common-regulators.dtsi, or at least, expose the proper regulator
> > hierarchy.
> 
> The USB and SATA regulators are just GPIO enabled switches (MOSFETs)
> or current limiters. I think these will always exist because of the
> reference designs. Or do you want to move them back into the board
> dts files? FWIW, I like it the way it is now. Not that I don't like
> it to be accurate.

At least providing the right hierarchy at the board level would be
great. Adding the -supply property to all our fixed regulators
wouldn't take too much code, and would be enough to model properly the
regulator trees.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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