linux-kernel - Re: [PATCH v4 1/2] dt-bindings: usb: ehci: add optional external vbus supply property

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Message-ID: <e3370b8d-2398-b4c0-c57c-978abd75c0f2@st.com>
Date:   Tue, 20 Mar 2018 09:10:38 +0000
From:   Amelie DELAUNAY <amelie.delaunay@...com>
To:     Rob Herring <robh@...nel.org>, Robin Murphy <robin.murphy@....com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>,
        Tony Prisk <linux@...sktech.co.nz>,
        Alan Stern <stern@...land.harvard.edu>,
        Roger Quadros <rogerq@...com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Linux USB List <linux-usb@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 1/2] dt-bindings: usb: ehci: add optional external vbus
 supply property



On 03/06/2018 03:40 PM, Rob Herring wrote:
> On Tue, Mar 6, 2018 at 8:09 AM, Robin Murphy <robin.murphy@....com> wrote:
>> On 06/03/18 01:57, Rob Herring wrote:
>>>
>>> On Thu, Mar 01, 2018 at 10:51:38AM +0100, Amelie Delaunay wrote:
>>>>
>>>> On some boards, especially when vbus supply requires large current,
>>>> and the charge pump on the PHY isn't enough, an external vbus power
>>>> switch
>>>> per port may be used.
>>>> Add portN_vbus-supply property to usb-ehci bindings. As the number of
>>>> ports
>>>> depends on the ehci controller, and the port on which an external vbus
>>>> supply depends on the platform, <portN> is used to make it generic.
>>>>
>>>> Signed-off-by: Amelie Delaunay <amelie.delaunay@...com>
>>>> ---
>>>>    Documentation/devicetree/bindings/usb/usb-ehci.txt | 1 +
>>>>    1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/usb/usb-ehci.txt
>>>> b/Documentation/devicetree/bindings/usb/usb-ehci.txt
>>>> index 3efde12..cd576db 100644
>>>> --- a/Documentation/devicetree/bindings/usb/usb-ehci.txt
>>>> +++ b/Documentation/devicetree/bindings/usb/usb-ehci.txt
>>>> @@ -19,6 +19,7 @@ Optional properties:
>>>>     - phys : phandle + phy specifier pair
>>>>     - phy-names : "usb"
>>>>     - resets : phandle + reset specifier pair
>>>> + - portN_vbus-supply : phandle of regulator supplying vbus for port N
>>>
>>>
>>> Just make this an array with the index being the port (and drop
>>> "portN_").
>>
>>
>> Does that still work if there is an external supply for port 1 but none for
>> port 0? I believe that was brought up as a possibility before.
> 
> Yes, if you use 0 or -1 to skip over an index.
> 
> Really, this should go in the connector node instead because Vbus is
> supplied to the connector, not the host controller. The connector
> binding is on its way into mainline.
> 
> Rob
> 

Not sure to catch what you mean by "make this an array" because 
regulator framework imposes <name>-supply: phandle to the regulator node.

I may have missed something around regulator consumers management ?

Do you meant something like
vbus-supply = <&reg_port0 &reg_port1>;
or in case there is an external supply for port 1 but none for port 0
vbus-supply = <-1 &reg_port1>;
?
If yes, a new API is needed in regulator framework to get an array of 
regulators ?


Regards,
Amelie