linux-kernel - Re: [PATCH v2 02/10] dt-bindings: iio: adc: ad7606: Make corrections on spi conditions

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Message-ID: <56090167-15a0-4386-89a6-c379d70faae6@baylibre.com>
Date: Tue, 24 Sep 2024 16:41:50 +0200
From: Guillaume Stols <gstols@...libre.com>
To: Conor Dooley <conor@...nel.org>
Cc: Uwe Kleine-König <ukleinek@...nel.org>,
 Lars-Peter Clausen <lars@...afoo.de>,
 Michael Hennerich <Michael.Hennerich@...log.com>,
 Jonathan Cameron <jic23@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>, Jonathan Corbet <corbet@....net>,
 linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-fbdev@...r.kernel.org, linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
 aardelean@...libre.com, dlechner@...libre.com, jstephan@...libre.com
Subject: Re: [PATCH v2 02/10] dt-bindings: iio: adc: ad7606: Make corrections
 on spi conditions

On 9/21/24 23:55, Conor Dooley wrote:
> On Fri, Sep 20, 2024 at 05:33:22PM +0000, Guillaume Stols wrote:
>> The SPI conditions are not always required, because there is also a
>> parallel interface. The way used to detect that the SPI interface is
>> used is to check if the reg value is between 0 and 256.
> And, yaknow, not that the bus you're on is a spi bus? I don't think this
> comment is relevant to the binding, especially given you have a property
> for it.

Apologies, I missed to change the commit message, it will be fixed in 
the next series.

Since Jonathan did not like very much inferring the interface with the 
reg's value that I used i the previous verison, I introduced this flag.

However this is only intended to be use in bindings, to determine 
whether or not spi properties should be added.

In the driver side of things, the bus interface is inferred by the 
parent's node (SPI driver is an module_spi_driver while parallel driver 
is module_platform_driver).

>
>> There is also a correction on the spi-cpha that is not required when SPI
>> interface is selected, while spi-cpol is.
> I don't see this change in your patch, there's no cpha in the before.
>
Again a problem with the commit message, this belongs now to another commit.
>> Signed-off-by: Guillaume Stols <gstols@...libre.com>
>> ---
>>   .../devicetree/bindings/iio/adc/adi,ad7606.yaml      | 20 +++++++++++++++++---
>>   1 file changed, 17 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
>> index 75334a033539..12995ebcddc2 100644
>> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
>> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
>> @@ -112,18 +112,32 @@ properties:
>>         assumed that the pins are hardwired to VDD.
>>       type: boolean
>>   
>> +  parallel-interface:
>> +    description:
>> +      If the parallel interface is used, be it directly or through a backend,
>> +      this property must be defined.
>> +    type: boolean
> The type you would want here is actually "flag", but I'm not sure why a
> property is needed. If you're using the parallel interface, why would
> you still be on a spi bus? I think I'm a bit confused here as to how
> this interface is supposed to be used.
>
> Thanks,
> Conor.
>
>> +
>>   required:
>>     - compatible
>>     - reg
>> -  - spi-cpol
>>     - avcc-supply
>>     - vdrive-supply
>>     - interrupts
>>     - adi,conversion-start-gpios
>>   
>> -allOf:
>> -  - $ref: /schemas/spi/spi-peripheral-props.yaml#
>> +oneOf:
>> +  - required:
>> +      - parallel-interface
>> +  - allOf:
>> +      - properties:
>> +          parallel-interface: false
>> +          spi-cpol: true
>> +      - $ref: /schemas/spi/spi-peripheral-props.yaml#
>> +      - required:
>> +          - spi-cpol
>>   
>> +allOf:
>>     - if:
>>         properties:
>>           compatible:
>>
>> -- 
>> 2.34.1
>>