[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 4:31 PM, Hans de Goede <hdegoede at redhat.com> wrote:
> Hi,
>
>
> On 31-07-15 08:35, Bruno Prémont wrote:
>>
>> On Fri, 31 Jul 2015 14:14:28 +0800 Chen-Yu Tsai wrote:
>>>
>>> On Fri, Jul 31, 2015 at 1:51 PM, Bruno Prémont 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 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?
>>
>>
>> If the device does not use the input there are two cases:
>> - ac-in and usb/otg in short-circuited (there is a bit in AXP registers
>>    to provide this indication)
>> - the unused one is just not connected/connectable
>>
>> In either case the voltage of the unused/unusable branch is not really
>> useful, nor is it useful to have it show up in sysfs.
>
>
> Exactly my thinking on this, +1 .
>
>>> 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.
>>
>>
>> Only those supplies effectively present (in-use or with connectors
>> to eventually use them) should be visible in sysfs.
>> Having more of them will just confuse the users, they would be searching
>> how they can connect the supply while there is no means to do so
>> except soldering to the tiny AXP pins.
>
>
> +1

OK. So mostly tablets and dev boards would benefit from having both
power supplies. Is there a preference for usb-power-supply over
vbus-det-gpio if both are available? Or just list them both and
let the driver sort it out?

Thanks.


ChenYu