linux-kernel - Re: [PATCH 1/6] dt-bindings: panel: explicitly list SPI CPHA and CPOL

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Message-ID: <1a03d894-3f4c-fb57-5f05-ad7bf11f5488@linaro.org>
Date:   Fri, 22 Jul 2022 20:37:49 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Markuss Broks <markuss.broks@...il.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Alexandru Tachici <alexandru.tachici@...log.com>,
        Marcelo Schmitt <marcelo.schmitt1@...il.com>,
        Tomislav Denis <tomislav.denis@....com>,
        Cosmin Tanislav <cosmin.tanislav@...log.com>,
        Nishant Malpani <nish.malpani25@...il.com>,
        Dragos Bogdan <dragos.bogdan@...log.com>,
        Nuno Sa <nuno.sa@...log.com>,
        Jean-Baptiste Maneyrol <jmaneyrol@...ensense.com>,
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        linux-spi@...r.kernel.org
Subject: Re: [PATCH 1/6] dt-bindings: panel: explicitly list SPI CPHA and CPOL

On 21/07/2022 21:30, Rob Herring wrote:
> On Thu, Jul 21, 2022 at 05:31:50PM +0200, Krzysztof Kozlowski wrote:
>> The spi-cpha and spi-cpol properties are device specific and should be
>> accepted only if device really needs them.  Explicitly list them in
>> device bindings in preparation of their removal from generic
>> spi-peripheral-props.yaml schema.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> ---
>>  .../bindings/display/panel/lgphilips,lb035q02.yaml   | 10 ++++++++++
>>  .../bindings/display/panel/samsung,ld9040.yaml       | 10 ++++++++++
>>  .../bindings/display/panel/samsung,lms380kf01.yaml   | 12 +++++++++---
>>  .../bindings/display/panel/samsung,lms397kf04.yaml   | 12 +++++++++---
>>  .../bindings/display/panel/samsung,s6d27a1.yaml      | 12 +++++++++---
>>  .../bindings/display/panel/sitronix,st7789v.yaml     | 10 ++++++++++
>>  .../devicetree/bindings/display/panel/tpo,td.yaml    | 10 ++++++++++
>>  7 files changed, 67 insertions(+), 9 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/display/panel/lgphilips,lb035q02.yaml b/Documentation/devicetree/bindings/display/panel/lgphilips,lb035q02.yaml
>> index 5e4e0e552c2f..0bd7bbad5b94 100644
>> --- a/Documentation/devicetree/bindings/display/panel/lgphilips,lb035q02.yaml
>> +++ b/Documentation/devicetree/bindings/display/panel/lgphilips,lb035q02.yaml
>> @@ -21,6 +21,16 @@ properties:
>>    enable-gpios: true
>>    port: true
>>  
>> +  spi-cpha:
>> +    type: boolean
>> +    description:
>> +      The device requires shifted clock phase (CPHA) mode.
>> +
>> +  spi-cpol:
>> +    type: boolean
>> +    description:
>> +      The device requires inverse clock polarity (CPOL) mode.
> 
> Not great duplicating the type and description everywhere.
> 
> We can move the definition back to spi-controller.yaml, so then that 
> does type checking of the property, but not presence/absence checks.

If I understand correctly, all client devices (which do no reference
spi-controller) will need to explicitly mention CPHA/CPOL. Good idea.

Best regards,
Krzysztof