Re: [PATCH v3 01/16] dt-bindings: usb: usb-hcd: Convert generic USB properties to DT schema

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On Wed, Oct 21, 2020 at 11:00:36AM +0800, Chunfeng Yun wrote:
> On Tue, 2020-10-20 at 14:20 +0300, Serge Semin wrote:
> > The generic USB HCD properties have been described in the legacy bindings
> > text file: Documentation/devicetree/bindings/usb/generic.txt . Let's
> > convert it' content into the USB HCD DT schema properties so all USB DT
>           ^ its?
> > nodes would be validated to have them properly utilized.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > 
> > ---
> > 
> > Changelog v2:
> > - Discard '|' in all the new properties, since we don't need to preserve
> >   the text formatting.
> > - Convert abbreviated form of the "maximum-speed" enum restriction into
> >   the multi-lined version of the list.
> > - Drop quotes from around the string constants.
> > ---
> >  .../devicetree/bindings/usb/generic.txt       | 57 ------------
> >  .../devicetree/bindings/usb/usb-hcd.yaml      | 88 +++++++++++++++++++

> Do we need change the file name or modify it's title?
> the title is "Generic USB Host Controller Device Tree Bindings", but
> some generic properties, such as, dr_mode, usb-role-switch, otg related
> ones, are usually used by DRD controller, this may cause some confusion.

Hm, good question. A problem of the naming and the properties inclusion do
exist here. I haven't thought that through when moved all the generic
properties into the usb-hcd.yaml bindings file. But I don't think it's a good
idea to rename the file. Most likely the best solution would be to split the
functionality up as follows:

1) usb.yaml - common USB controller with generic properties for all USB modes (host, peripheral, otg):
   + $nodename
   + phys
   + phy-names
   + usb-phy
   + maximum-speed
   + phy_type
2) usb-hcd.yaml - DT schema for USB host controllers (EHCI/OHCI/UHCI):
   + allOf: [usb.yaml#]
   + companion
3) usb-xhci.yaml - DT schema for USB host controllers (xHCI):
   + allOf: [usb-hcd.yaml#]
   + usb2-lpm-disable
   + usb3-lpm-capable
   + quirk-broken-port-ped
   + imod-interval-ns
4) usb-drd.yaml - DT schema for USB OTG controllers:
   + otg-rev
   + hnp-disable
   + srp-disable
   + adp-disable
   + usb-role-switch
   + role-switch-default-mode
   + tpl-support
   + dr_mode: [host, peripheral, otg]

So in case if an USB controller is DRD with EHCI host, then it will need
to pass evaluation of allOf: [usb-hcd.yaml#, usb-drd.yaml#]. If an USB
controller is DRD with xHCI host, then the next schema can be applied:
[usb-xhci.yaml#, usb-drd.yaml#]. A conditional schema is also applicable
here, like this:
allOf:
  - $ref: usb-drd.yaml#
  - if:
      properties:
        dr_mode:
          const: host
    then:
      $ref: usb-hcd.yaml# (or usb-xhci.yaml#)
    else:
      #ref: usb.yaml#

What do you think? @Rob, @Greg, we need your opinion here.

-Sergey

> 
> >  2 files changed, 88 insertions(+), 57 deletions(-)
> >  delete mode 100644 Documentation/devicetree/bindings/usb/generic.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/generic.txt b/Documentation/devicetree/bindings/usb/generic.txt
> > deleted file mode 100644
> > index ba472e7aefc9..000000000000
> > --- a/Documentation/devicetree/bindings/usb/generic.txt
> > +++ /dev/null
> > @@ -1,57 +0,0 @@
> > -Generic USB Properties
> > -
> > -Optional properties:
> > - - maximum-speed: tells USB controllers we want to work up to a certain
> > -			speed. Valid arguments are "super-speed-plus",
> > -			"super-speed", "high-speed", "full-speed" and
> > -			"low-speed". In case this isn't passed via DT, USB
> > -			controllers should default to their maximum HW
> > -			capability.
> > - - dr_mode: tells Dual-Role USB controllers that we want to work on a
> > -			particular mode. Valid arguments are "host",
> > -			"peripheral" and "otg". In case this attribute isn't
> > -			passed via DT, USB DRD controllers should default to
> > -			OTG.
> > - - phy_type: tells USB controllers that we want to configure the core to support
> > -			a UTMI+ PHY with an 8- or 16-bit interface if UTMI+ is
> > -			selected. Valid arguments are "utmi" and "utmi_wide".
> > -			In case this isn't passed via DT, USB controllers should
> > -			default to HW capability.
> > - - otg-rev: tells usb driver the release number of the OTG and EH supplement
> > -			with which the device and its descriptors are compliant,
> > -			in binary-coded decimal (i.e. 2.0 is 0200H). This
> > -			property is used if any real OTG features(HNP/SRP/ADP)
> > -			is enabled, if ADP is required, otg-rev should be
> > -			0x0200 or above.
> > - - companion: phandle of a companion
> > - - hnp-disable: tells OTG controllers we want to disable OTG HNP, normally HNP
> > -			is the basic function of real OTG except you want it
> > -			to be a srp-capable only B device.
> > - - srp-disable: tells OTG controllers we want to disable OTG SRP, SRP is
> > -			optional for OTG device.
> > - - adp-disable: tells OTG controllers we want to disable OTG ADP, ADP is
> > -			optional for OTG device.
> > - - usb-role-switch: boolean, indicates that the device is capable of assigning
> > -			the USB data role (USB host or USB device) for a given
> > -			USB connector, such as Type-C, Type-B(micro).
> > -			see connector/usb-connector.yaml.
> > - - role-switch-default-mode: indicating if usb-role-switch is enabled, the
> > -			device default operation mode of controller while usb
> > -			role is USB_ROLE_NONE. Valid arguments are "host" and
> > -			"peripheral". Defaults to "peripheral" if not
> > -			specified.
> > -
> > -
> > -This is an attribute to a USB controller such as:
> > -
> > -dwc3@4a030000 {
> > -	compatible = "synopsys,dwc3";
> > -	reg = <0x4a030000 0xcfff>;
> > -	interrupts = <0 92 4>
> > -	usb-phy = <&usb2_phy>, <&usb3,phy>;
> > -	maximum-speed = "super-speed";
> > -	dr_mode = "otg";
> > -	phy_type = "utmi_wide";
> > -	otg-rev = <0x0200>;
> > -	adp-disable;
> > -};
> > diff --git a/Documentation/devicetree/bindings/usb/usb-hcd.yaml b/Documentation/devicetree/bindings/usb/usb-hcd.yaml
> > index 7263b7f2b510..ee7ea205c71d 100644
> > --- a/Documentation/devicetree/bindings/usb/usb-hcd.yaml
> > +++ b/Documentation/devicetree/bindings/usb/usb-hcd.yaml
> > @@ -22,9 +22,97 @@ properties:
> >      description:
> >        Name specifier for the USB PHY
> >  
> > +  maximum-speed:
> > +   description:
> > +     Tells USB controllers we want to work up to a certain speed. In case this
> > +     isn't passed via DT, USB controllers should default to their maximum HW
> > +     capability.
> > +   $ref: /schemas/types.yaml#/definitions/string
> > +   enum:
> > +     - low-speed
> > +     - full-speed
> > +     - high-speed
> > +     - super-speed
> > +     - super-speed-plus
> > +
> > +  dr_mode:
> > +    description:
> > +      Tells Dual-Role USB controllers that we want to work on a particular
> > +      mode. In case this attribute isn't passed via DT, USB DRD controllers
> > +      should default to OTG.
> > +    $ref: /schemas/types.yaml#/definitions/string
> > +    enum: [host, peripheral, otg]
> > +
> > +  phy_type:
> > +    description:
> > +      Tells USB controllers that we want to configure the core to support a
> > +      UTMI+ PHY with an 8- or 16-bit interface if UTMI+ is selected. In case
> > +      this isn't passed via DT, USB controllers should default to HW
> > +      capability.
> > +    $ref: /schemas/types.yaml#/definitions/string
> > +    enum: [utmi, utmi_wide]
> > +
> > +  otg-rev:
> > +    description:
> > +      Tells usb driver the release number of the OTG and EH supplement with
> > +      which the device and its descriptors are compliant, in binary-coded
> > +      decimal (i.e. 2.0 is 0200H). This property is used if any real OTG
> > +      features (HNP/SRP/ADP) is enabled. If ADP is required, otg-rev should be
> > +      0x0200 or above.
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +  companion:
> > +    description: Phandle of a companion device
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +
> > +  hnp-disable:
> > +    description:
> > +      Tells OTG controllers we want to disable OTG HNP. Normally HNP is the
> > +      basic function of real OTG except you want it to be a srp-capable only B
> > +      device.
> > +    type: boolean
> > +
> > +  srp-disable:
> > +    description:
> > +      Tells OTG controllers we want to disable OTG SRP. SRP is optional for OTG
> > +      device.
> > +    type: boolean
> > +
> > +  adp-disable:
> > +    description:
> > +      Tells OTG controllers we want to disable OTG ADP. ADP is optional for OTG
> > +      device.
> > +    type: boolean
> > +
> > +  usb-role-switch:
> > +    description:
> > +      Indicates that the device is capable of assigning the USB data role
> > +      (USB host or USB device) for a given USB connector, such as Type-C,
> > +      Type-B(micro). See connector/usb-connector.yaml.
> > +
> > +  role-switch-default-mode:
> > +    description:
> > +      Indicates if usb-role-switch is enabled, the device default operation
> > +      mode of controller while usb role is USB_ROLE_NONE.
> > +    $ref: /schemas/types.yaml#/definitions/string
> > +    enum: [host, peripheral]
> > +    default: peripheral
> > +
> >  examples:
> >    - |
> >      usb {
> >          phys = <&usb2_phy1>, <&usb3_phy1>;
> >          phy-names = "usb";
> >      };
> > +  - |
> > +    usb@4a030000 {
> > +        compatible = "snps,dwc3";
> > +        reg = <0x4a030000 0xcfff>;
> > +        interrupts = <0 92 4>;
> > +        usb-phy = <&usb2_phy>, <&usb3_phy>;
> > +        maximum-speed = "super-speed";
> > +        dr_mode = "otg";
> > +        phy_type = "utmi_wide";
> > +        otg-rev = <0x0200>;
> > +        adp-disable;
> > +    };
> 



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