linux-kernel - Re: [PATCH 1/2] dt-bindings: phy: add support for NXPs TJA1145 CAN transceiver

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Message-ID: <20250731044824.GA3815@legfed1>
Date: Thu, 31 Jul 2025 06:48:24 +0200
From: Dimitri Fedrau <dima.fedrau@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Dimitri Fedrau <dimitri.fedrau@...bherr.com>,
	Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-phy@...ts.infradead.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: phy: add support for NXPs TJA1145 CAN
 transceiver

Hi Krzysztof,

Am Wed, Jul 30, 2025 at 09:35:12AM +0200 schrieb Krzysztof Kozlowski:
> On Mon, Jul 28, 2025 at 05:39:29PM +0200, Dimitri Fedrau wrote:
> > Adding documentation for NXPs TJA1145 CAN transceiver.
> > 
> > Signed-off-by: Dimitri Fedrau <dimitri.fedrau@...bherr.com>
> > ---
> >  .../devicetree/bindings/phy/nxp,tja1145-can.yaml   | 79 ++++++++++++++++++++++
> 
> Why isn't this in can directory with rest of CAN bindings?
> 
The directory contains CAN controller bindings. This is a CAN transceiver
binding. And the only CAN transceiver binding I could find so far is this:
https://elixir.bootlin.com/linux/v6.16/source/Documentation/devicetree/bindings/phy/ti,tcan104x-can.yaml
The driver uses the generic PHY framework as the driver for the tja1145
does.

> >  1 file changed, 79 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/phy/nxp,tja1145-can.yaml b/Documentation/devicetree/bindings/phy/nxp,tja1145-can.yaml
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..10bf2bce1b35788b3284c42e544a56eda6d79947
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/nxp,tja1145-can.yaml
> 
> Filename should match compatible.
> 
Ok, will fix this.

> > @@ -0,0 +1,79 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/phy/nxp,tja1145-can.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: TJA1145 CAN transceiver
> > +
> > +maintainers:
> > +  - Dimitri Fedrau <dimitri.fedrau@...bherr.com>
> > +
> > +allOf:
> > +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> 
> Missing ref to transceiver properties. Look at other CAN bindings.
>
There is only one transceiver property(max-bitrate) which I don't need
because the max-bitrate is known for the device. So why should I add it
to the DT ?
I'm only aware of CAN controller bindings making use of the transceiver
property which I think is because the PHYs they are supporting with this
are very simple which need no or little configuration to operate and the
max-bitrate property is needed to limit the bitrate.

> > +
> > +properties:
> > +  compatible:
> > +    const: nxp,tja1145
> > +
> > +  "#phy-cells":
> > +    const: 0
> > +
> > +  reg:
> > +    maxItems: 1
> 
> reg is the second property, also in "required:" block.
> 
Will fix this.

> > +
> > +  spi-max-frequency:
> > +    maximum: 4000000
> > +
> > +  spi-cpha: true
> > +
> > +  spi-cs-setup-delay-ns:
> > +    minimum: 50
> > +    default: 50
> > +
> > +  spi-cs-hold-delay-ns:
> > +    minimum: 50
> > +    default: 50
> > +
> > +  spi-cs-inactive-delay-ns:
> > +    minimum: 250
> > +    default: 250
> > +
> > +  vcc-supply:
> > +    description:
> > +      CAN transceiver supply voltage
> > +
> > +  vio-supply:
> > +    description:
> > +      Supply voltage for I/O level adaptor
> > +
> > +  vbat-supply:
> > +    description:
> > +      Battery supply voltage
> > +
> > +required:
> > +  - compatible
> > +  - "#phy-cells"
> > +  - reg
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > +  - |
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +        canphy@0 {
> 
> can-phy if something like this exist. If not, then probably can-transceiver
>
Will fix this.

> > +            compatible = "nxp,tja1145";
> > +            #phy-cells = <0>;
> > +            reg = <0>;
> 
> Please follow DTS coding style.
>
Ok.

Best regards,
Dimitri Fedrau