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

From: Serge Semin
Date: Wed Oct 21 2020 - 11:46:37 EST

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;
> > + };
>