Date:   Fri, 26 Aug 2022 09:20:35 +0200
From:   Dario Binacchi <dario.binacchi@...rulasolutions.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     linux-kernel@...r.kernel.org,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Amarula patchwork <linux-amarula@...rulasolutions.com>,
        michael@...rulasolutions.com,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Dario Binacchi <dariobin@...ero.it>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        devicetree@...r.kernel.org, linux-can@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [RFC PATCH 1/4] dt-bindings: net: can: add STM32 bxcan DT bindings

Hi Krzysztof,

On Mon, Aug 22, 2022 at 7:39 PM Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:
>
> On 20/08/2022 11:08, Dario Binacchi wrote:
> > Hi Krzysztof,
> >
> > On Thu, Aug 18, 2022 at 10:22 AM Krzysztof Kozlowski
> > <krzysztof.kozlowski@...aro.org> wrote:
> >>
> >> On 17/08/2022 17:35, Dario Binacchi wrote:
> >>> Add documentation of device tree bindings for the STM32 basic extended
> >>> CAN (bxcan) controller.
> >>>
> >>> Signed-off-by: Dario Binacchi <dariobin@...ero.it>
> >>> Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
> >>
> >> You do not need two SoBs. Keep only one, matching the From field.
> >
> > I started implementing this driver in my spare time, so my intention
> > was to keep track of it.
>
> SoB is not related to copyrights. Keep personal copyrights (with/next to
> work ones), but SoB is coming from a person and that's only one. Choose
> one "person".

Ok, I got it.

>
> >
> >>
> >>> ---
> >>>
> >>>  .../devicetree/bindings/net/can/st,bxcan.yaml | 139 ++++++++++++++++++
> >>>  1 file changed, 139 insertions(+)
> >>>  create mode 100644 Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/net/can/st,bxcan.yaml b/Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> >>> new file mode 100644
> >>> index 000000000000..f4cfd26e4785
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/net/can/st,bxcan.yaml
> >>
> >> File name like compatible, so st,stm32-bxcan-core.yaml (or some other
> >> name, see comment later)
> >
> >>
> >>> @@ -0,0 +1,139 @@
> >>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/net/can/st,bxcan.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> +
> >>> +title: STMicroelectronics bxCAN controller Device Tree Bindings
> >>
> >> s/Device Tree Bindings//
> >
> >>
> >>> +
> >>> +description: STMicroelectronics BxCAN controller for CAN bus
> >>> +
> >>> +maintainers:
> >>> +  - Dario Binacchi <dario.binacchi@...rulasolutions.com>
> >>> +
> >>> +allOf:
> >>> +  - $ref: can-controller.yaml#
> >>> +
> >>> +properties:
> >>> +  compatible:
> >>> +    enum:
> >>> +      - st,stm32-bxcan-core
> >>
> >> compatibles are supposed to be specific. If this is some type of
> >> micro-SoC, then it should have its name/number. If it is dedicated
> >> device, is the final name bxcan core? Google says  the first is true, so
> >> you miss specific device part.
> >
> > I don't know if I understand correctly, I hope the change in version 2
> > is what you requested.
>
> What is the name of the SoC, where this is in?

STM32F4

>
> >
> >>
> >>> +
> >>> +  reg:
> >>> +    maxItems: 1
> >>> +
> >>> +  resets:
> >>> +    maxItems: 1
> >>> +
> >>> +  clocks:
> >>> +    description:
> >>> +      Input clock for registers access
> >>> +    maxItems: 1
> >>> +
> >>> +  '#address-cells':
> >>> +    const: 1
> >>> +
> >>> +  '#size-cells':
> >>> +    const: 0
> >>> +
> >>> +required:
> >>> +  - compatible
> >>> +  - reg
> >>> +  - resets
> >>> +  - clocks
> >>> +  - '#address-cells'
> >>> +  - '#size-cells'
> >>> +
> >>> +additionalProperties: false
> >>> +
> >>> +patternProperties:
> >>
> >> This goes after "properties: in top level (before "required").
> >>
> >>> +  "^can@[0-9]+$":
> >>> +    type: object
> >>> +    description:
> >>> +      A CAN block node contains two subnodes, representing each one a CAN
> >>> +      instance available on the machine.
> >>> +
> >>> +    properties:
> >>> +      compatible:
> >>> +        enum:
> >>> +          - st,stm32-bxcan
> >>
> >> Why exactly do you need compatible for the child? Is it an entierly
> >> separate device?
> >
> > I took inspiration from other drivers for ST microcontroller
> > peripherals (e. g. drivers/iio/adc/stm32-adc-core.c,
> > drivers/iio/adc/stm32-adc.c) where
> > some resources are shared between the peripheral instances. In the
> > case of CAN, master (CAN1) and slave (CAN2) share the registers for
> > configuring the filters and the clock.
> > In the core module you can find the functions about the shared
> > resources, while the childrens implement the driver.
>
> In both cases you refer to the driver, but we talk here about bindings
> which are rather not related. So I repeat the question - is the child
> entirely separate device which can be used in other devices?

IMHO, I think so.

Thanks and regards,
Dario
>
>
> Best regards,
> Krzysztof



-- 

Dario Binacchi

Embedded Linux Developer

dario.binacchi@...rulasolutions.com

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T. +39 042 243 5310
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