Re: [PATCH 4/7] dt-bindings: spi: stm32: add bindings regarding stm32h7 spi slave

[Valentin CARON <valentin.caron@foss.st.com>]

On 4/28/23 23:46, Rob Herring wrote:
> On Fri, Apr 28, 2023 at 02:15:21PM +0200, Valentin Caron wrote:
>> From: Alain Volmat <alain.volmat@foss.st.com>
>>
>> Update the spi-stm32 binding yaml regarding to the SPI slave support.
> Why? What problem are you trying to solve.
To add some documentation about cs-gpios and don't allow to use
spi-slave property with st,stm32f4-spi compatible.

I will specify this in next patchset.

>
>> Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
>> Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
>> ---
>>   Documentation/devicetree/bindings/spi/st,stm32-spi.yaml | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml b/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
>> index c599eb359d56..1d26fa2658c5 100644
>> --- a/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
>> +++ b/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
>> @@ -27,6 +27,7 @@ allOf:
>>       then:
>>         properties:
>>           st,spi-midi-ns: false
>> +        spi-slave: false
>>   
>>   properties:
>>     "#address-cells": true
>> @@ -62,6 +63,13 @@ properties:
>>         - const: rx
>>         - const: tx
>>   
>> +  cs-gpios:
>> +    description:
>> +      In case of spi-slave not defined, cs-gpios behave as defined in
>> +      spi-controller.yaml.
>> +      In case of spi-slave defined, if <0>, indicate that SS should be
>> +      detected via the dedicated HW pin
> I don't understand. I though cs-gpios was for master mode. You want to
> define 'cs-gpios = <0>;'? How would that be different than just omitting
> cs-gpios?
>
> Rob
We try to keep consistency with spi master, but, as you said, it is useless.
I will remove it in next patchset.

Thanks,
Valentin