linux-kernel - Re: [PATCH v2 1/3] dt-bindings: phy: Add Cygnus usb phy binding

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Message-ID: <CAAFb_vq+qyA6mEyOEG2kHXS73wsBx8WZTWhWpKn+ouwPk0qY=A@mail.gmail.com>
Date:   Tue, 14 Nov 2017 10:59:10 +0530
From:   Raveendra Padasalagi <raveendra.padasalagi@...adcom.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Russell King <linux@...linux.org.uk>,
        Scott Branden <sbranden@...adcom.com>,
        Ray Jui <rjui@...adcom.com>,
        Srinath Mannam <srinath.mannam@...adcom.com>,
        Vikram Prakash <vikram.prakash@...adcom.com>,
        Jon Mason <jonmason@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Raviteja Garimella <raviteja.garimella@...adcom.com>,
        Rafal Milecki <rafal@...ecki.pl>,
        Arnd Bergmann <arnd@...db.de>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Jaehoon Chung <jh80.chung@...sung.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH v2 1/3] dt-bindings: phy: Add Cygnus usb phy binding

Hi Rob,

On Mon, Nov 13, 2017 at 11:23 PM, Rob Herring <robh@...nel.org> wrote:
> On Sun, Nov 12, 2017 at 10:23 PM, Raveendra Padasalagi
> <raveendra.padasalagi@...adcom.com> wrote:
>> Hi,
>>
>> On Sat, Nov 11, 2017 at 3:14 AM, Rob Herring <robh@...nel.org> wrote:
>>> On Wed, Nov 08, 2017 at 01:16:41PM +0530, Raveendra Padasalagi wrote:
>>>> Add devicetree binding document for broadcom's
>>>> Cygnus SoC specific usb phy controller driver.
>>>>
>>>> Signed-off-by: Raveendra Padasalagi <raveendra.padasalagi@...adcom.com>
>>>> ---
>>>>  .../bindings/phy/brcm,cygnus-usb-phy.txt           | 106 +++++++++++++++++++++
>>>>  1 file changed, 106 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/phy/brcm,cygnus-usb-phy.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/phy/brcm,cygnus-usb-phy.txt b/Documentation/devicetree/bindings/phy/brcm,cygnus-usb-phy.txt
>>>> new file mode 100644
>>>> index 0000000..bbc4b94
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/phy/brcm,cygnus-usb-phy.txt
>>>> @@ -0,0 +1,106 @@
>>>> +BROADCOM CYGNUS USB PHY
>>>> +
>>>> +Required Properties:
>>>> +- compatible:  brcm,cygnus-usb-phy
>>>> +- reg : the register start address and length for
>>>> +        crmu_usbphy_aon_ctrl,
>>>> +        cdru usb phy control,
>>>> +        usb host idm registers,
>>>> +        usb device idm registers.
>>>> +- reg-names: a list of the names corresponding to the previous register ranges
>>>> +  Should contain
>>>> +        "crmu-usbphy-aon-ctrl",
>>>> +        "cdru-usbphy",
>>>> +        "usb2h-idm",
>>>> +        "usb2d-idm".
>>>> +- address-cells: should be 1
>>>> +- size-cells: should be 0
>>>> +
>>>> +Sub-nodes:
>>>> +  Each port's PHY should be represented as a sub-node.
>>>> +
>>>> +Sub-nodes required properties:
>>>> +- reg: the PHY number
>>>> +- #phy-cells must be 1
>>>> +  The node that uses the phy must provide 1 integer argument specifying
>>>> +  port number.
>>>> +
>>>> +Optional Properties:
>>>> +- vbus-p#-supply : The regulator for vbus out control for the host
>>>
>>> Is this a literal # or something else?
>>
>> Yes, this is a literal. It's assumed # will replace numeric 0-2 for
>> each of the ports.
>
> I'm still confused. Which is valid? "vbus-p#-supply" or "vbus-p0-supply"
>
I agree, it's creating confusion. Instead of enumerating
"vbus-p0-supply", "vbus-p1-supply", "vbus-p2-supply" kept "vbus-p#-supply".

Yes, as suggested by you "vbus-supply" should be sufficient as it's in each
of phy sub node.

> If the latter, you need to enumerate all valid options. But these are
> in sub nodes for each port, so just "vbus-supply" should be
> sufficient.

Keeping "vbus-supply" should not create any confusion. Will send out the
change in next version of the patch.

> One more question, does Vbus actually supply power to the phy or you
> are just associating the Vbus supply to a connector with a port? The
> latter needs a connector node instead and Vbus should be part of that.
> There's been some attempts at USB connectors, but we don't really have
> one yet (the extcon binding is not it).

Vbus is not supplied to phy, it's been given to the devices connected on
the port and in our platform vbus is controlled through an external regulator
which is controlled through gpio.
So "vbus-supply" shown above actually points to the phandle of vbus regulator
node.

>> In the example it's not shown as the regulators specified in vbus-p#-supply
>> are board specific.
>
> Please show in the example. Examples should be complete.

Ok. Sure.

> Rob