RE: [PATCH 3/3] dt-bindings: usb: add documentation for aspeed udc

Neal Liu
2022-05-16T03:34:34Z

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Sunday, May 15, 2022 4:22 AM
> To: Neal Liu <neal_liu@aspeedtech.com>; Greg Kroah-Hartman
> <gregkh@linuxfoundation.org>; Rob Herring <robh+dt@kernel.org>; Krzysztof
> Kozlowski <krzysztof.kozlowski+dt@linaro.org>; Joel Stanley <joel@jms.id.au>;
> Andrew Jeffery <andrew@aj.id.au>; Felipe Balbi <balbi@kernel.org>; Sumit
> Semwal <sumit.semwal@linaro.org>; Christian König
> <christian.koenig@amd.com>; Geert Uytterhoeven <geert@linux-m68k.org>;
> Li Yang <leoyang.li@nxp.com>
> Cc: linux-aspeed@lists.ozlabs.org; linux-usb@vger.kernel.org;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-kernel@vger.kernel.org; linux-media@vger.kernel.org;
> dri-devel@lists.freedesktop.org; linaro-mm-sig@lists.linaro.org; BMC-SW
> <BMC-SW@aspeedtech.com>
> Subject: Re: [PATCH 3/3] dt-bindings: usb: add documentation for aspeed udc
>
> On 13/05/2022 17:39, Neal Liu wrote:
> >> -----Original Message-----
> >> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >> Sent: Friday, May 13, 2022 5:07 PM
> >> To: Neal Liu <neal_liu@aspeedtech.com>; Greg Kroah-Hartman
> >> <gregkh@linuxfoundation.org>; Rob Herring <robh+dt@kernel.org>;
> >> Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>; Joel Stanley
> >> <joel@jms.id.au>; Andrew Jeffery <andrew@aj.id.au>; Felipe Balbi
> >> <balbi@kernel.org>; Sumit Semwal <sumit.semwal@linaro.org>; Christian
> >> König <christian.koenig@amd.com>; Geert Uytterhoeven <geert@linux-
> >> m68k.org>; Li Yang <leoyang.li@nxp.com>
> >> Cc: linux-aspeed@lists.ozlabs.org; linux-usb@vger.kernel.org;
> >> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> >> linux- kernel@vger.kernel.org; linux-media@vger.kernel.org; dri-
> >> devel@lists.freedesktop.org; linaro-mm-sig@lists.linaro.org; BMC-SW
> >> <BMC- SW@aspeedtech.com>
> >> Subject: Re: [PATCH 3/3] dt-bindings: usb: add documentation for
> >> aspeed udc
> >>
> >> On 13/05/2022 08:57, Neal Liu wrote:
> >>> Add device tree binding documentation for the Aspeed USB2.0 Device
> >>> Controller.
> >>>
> >>> Signed-off-by: Neal Liu <neal_liu@aspeedtech.com>
> >>> ---
> >>> .../devicetree/bindings/usb/aspeed,udc.yaml | 52
> >> +++++++++++++++++++
> >>> 1 file changed, 52 insertions(+)
> >>> create mode 100644
> >>> Documentation/devicetree/bindings/usb/aspeed,udc.yaml
> >>
> >> Please name the file as first compatible, so "aspeed,ast2600-udc.yaml"
> >
> > Okay, I could rename it for next patch if you preferred.
> > But there are lots of yaml files which are not named as first compatible.
>
> Yes, I know, I quite likely I also produced such bindings, but a specific name is
> rather preferred. Otherwise you will have a difficult naming choice when your
> next Aspeed UDC requires new bindings file because of some differences (not
> yet known now).
>
We can rename the bindings if next Aspeed UDC needs, don't you think?
Currently, Aspeed has no requirement.
> >
> >>
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/usb/aspeed,udc.yaml
> >>> b/Documentation/devicetree/bindings/usb/aspeed,udc.yaml
> >>> new file mode 100644
> >>> index 000000000000..d1d2f77d1c54
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/usb/aspeed,udc.yaml
> >>> @@ -0,0 +1,52 @@
> >>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) #
> >>> +Copyright
> >>> +(c) 2020 Facebook Inc.
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/usb/aspeed,udc.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> +
> >>> +title: ASPEED USB 2.0 Device Controller
> >>> +
> >>> +maintainers:
> >>> + - Neal Liu <neal_liu@aspeedtech.com>
> >>> +
> >>> +description: |+
> >>> + The ASPEED USB 2.0 Device Controller implements 1 control
> >>> +endpoint and
> >>> + 4 generic endpoints for AST260x.
> >>> +
> >>> + Supports independent DMA channel for each generic endpoint.
> >>> + Supports 32/256 stages descriptor mode for all generic endpoints.
> >>> +
> >>> +properties:
> >>> + compatible:
> >>> + enum:
> >>> + - aspeed,ast2600-udc
> >>> +
> >>> + reg:
> >>> + maxItems: 1
> >>> +
> >>> + clocks:
> >>> + maxItems: 1
> >>> +
> >>> + interrupts:
> >>> + maxItems: 1
> >>
> >> No child properties? No ports or any other devices? No usb-hcd.yaml?
> >
> > Aspeed udc only has 1 port, no need extra properties for now.
>
> OK
>
> >
> >>> +
> >>> +required:
> >>> + - compatible
> >>> + - reg
> >>> + - clocks
> >>> + - interrupts
> >>> +
> >>> +additionalProperties: false
> >>> +
> >>> +examples:
> >>> + - |
> >>> + #include <dt-bindings/clock/aspeed-clock.h>
> >>> + udc: udc@1e6a2000 {
> >>
> >> Node name: usb
> >
> > "udc" is more recognizable than "usb" I think. "usb" is too general, can be
> various like host or device.
>
> It's still required by schema for most of USB host controllers. Existing USB
> device controllers use usb as well (except Atmel mentioning gadget) Generic
> name is also expected by Devicetree spec and "udc" is not on a list of
> examples of generic names (usb is).

Okay, I'll revise it for next patch.
Thanks

>
>
> Best regards,
> Krzysztof