[linux-sunxi] [PATCH 6/8] ARM: dts: axp209: Add usb_power_supply child node to the ax209 node

[Chen-Yu Tsai]

On Fri, Jul 31, 2015 at 1:51 PM, Bruno Prémont
<bonbons at linux-vserver.org> wrote:
> Hi ChenYu,
>
> On Fri, 31 Jul 2015 13:31:53 +0800 Chen-Yu Tsai wrote:
>> Hi Hans,
>>
>> On Wed, Jun 10, 2015 at 5:37 AM, Hans de Goede <hdegoede at redhat.com> wrote:
>> > Add a node representing the usb power supply part of the axp209 pmic, note
>> > that the usb power supply and the (to be added later) ac power supply will
>> > each have their own child-node, so that they can be separately specified
>> > as power-supply for other nodes using a power-supply property with a
>> > phandle pointing to the right axp209 child-node.
>> >
>> > Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>> > ---
>> >  arch/arm/boot/dts/axp209.dtsi | 5 +++++
>> >  1 file changed, 5 insertions(+)
>> >
>> > diff --git a/arch/arm/boot/dts/axp209.dtsi b/arch/arm/boot/dts/axp209.dtsi
>> > index 24c935c..051ab3b 100644
>> > --- a/arch/arm/boot/dts/axp209.dtsi
>> > +++ b/arch/arm/boot/dts/axp209.dtsi
>> > @@ -89,4 +89,9 @@
>> >                         regulator-name = "ldo5";
>> >                 };
>> >         };
>> > +
>> > +       usb_power_supply: usb_power_supply {
>> > +               compatible = "x-powers,axp202-usb-power-supply";
>> > +               status = "disabled";
>>
>> Is there any reason to have this disabled by default?
>> AFAIK this is not something configurable in hardware,
>> and the driver just gives readouts and status updates.
>
> There are some devices that only have 'AC-IN' instead of usb/otg power
> (set-top boxes) so having the devices tell what power sources they
> have makes sense (otherwise those that have ac-in instead of otg would
> have to disable usb_power_supply) and avoids confusion by explicitly
> stating presence in device dts.

That's true. But this is a bit of hardware inside the AXP.
If it's power isn't routed, it should report it, shouldn't it?

And normal users would probably expect to read the input
voltage/current/status through sysfs (or maybe hwmon?),
instead of not finding the device and having to look through
the DTS.

If you're using a distro, you might not have the kernel sources
around, and digging through the in-system device tree isn't that
straightforward if you don't know where to look.

> NB: I should hopefully get my battery supply driver ported this WE,
> ac-in/rtc are done, this WE. I'm going to default-off for them as well
> (note that for some extra details should be provided in dts).

I'm guessing we won't be using the axp288 one?

Thanks
ChenYu

> Bruno
>
>> ChenYu
>>
>> > +       };
>> >  };
>> > --
>> > 2.3.6