linux-kernel - Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

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Message-ID: <ZaVtNmvRjPAn9bph@cjw-notebook>
Date: Mon, 15 Jan 2024 18:36:54 +0100
From: Christoph Winklhofer <cj.winklhofer@...il.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Rob Herring <robh@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Jonathan Corbet <corbet@....net>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

On Sun, Jan 14, 2024 at 04:55:42PM +0100, Krzysztof Kozlowski wrote:
> On 14/01/2024 15:47, Christoph Winklhofer wrote:
> > On Sun, Jan 14, 2024 at 11:54:48AM +0100, Krzysztof Kozlowski wrote:
> >> On 13/01/2024 19:04, Christoph Winklhofer wrote:
> >>> On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
> >>>> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
> >>>>> Add device tree binding for UART 1-Wire bus.
> >>>>>
> >>>>> Signed-off-by: Christoph Winklhofer <cj.winklhofer@...il.com>
> >>>>> ---
> >>>>>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
> >>>>>  1 file changed, 62 insertions(+)
> >>>>>
> >>>>> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>>>> new file mode 100644
> >>>>> index 000000000000..6b90693b2ca0
> >>>>> --- /dev/null
> >>>>> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>>>> @@ -0,0 +1,62 @@
> >>>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> >>>>> +%YAML 1.2
> >>>>> +---
> >>>>> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
> >>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> ...
> >>>>> +properties:
> >>>>> +  compatible:
> >>>>> +    const: w1-uart
> >>>>> +
> >>>>> +  reset-speed:
> >>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>>>> +    default: 9600
> >>>>> +    description: |
> >>>>
> >>>> Don't need '|' if no formatting
> >>>>
> >>>
> >>> Ok.
> >>>
> >>>>> +      The baud rate for the 1-Wire reset and presence detect.
> >>>>> +
> >>>>> +  touch_0-speed:
> >>>>
> >>>> Don't use '_' in property names.
> >>>>
> >>>> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
> >>>> here. I assume these are low and high times which are a function of the 
> >>>> baudrate.
> >>>>
> >>>
> >>> I change the name to 'write-0-speed' and 'write-1-speed'. The function
> >>> in the w1-framework is named 'touch_bit' - therefore the previous
> >>> naming. 
> >>>
> >>> It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
> >>> (write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
> >>> reads a 0-Bit or 1-Bit (write-1-speed).
> >>
> >>
> >> Then probably -bps:
> >> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
> > 
> > The serial.yaml uses prefix -speed for the baud rate but I can change it
> > to -bps.
> 
> Do you reference serial.yaml?
> 

No, serial.yaml is not referenced but 'onewire' will be a child-node of
a serial-device which already defines baud rate related properties
with -speed (e.g. max-speed although not used in w1-uart). Hence, I
thought -speed is typically used for baud rates.

Thanks,
Christoph