Re: [PATCH 1/4] dt-bindings: spi: amlogic,a1-spifc: make power-domains required

[neil.armstrong@linaro.org]

On 10/07/2024 18:23, George Stark wrote:
> Hello Krzysztof, Neil, Rob
> 
> Thanks for your reviews.
> 
> I'd just like to clarify things a little on that matter. On A1 most of
> periphery has either dedicated power domain (ir, spifc, spi, cpu etc) or
> several peripheries share single PD e.g. pwm, temp sensor, i2c, adc
> share PD 12. Appropriate PD must be turned on before the periphery is
> touched and be on while periphery is used. Experiments confirm it. So
> power-domains property in dts nodes is really required. It makes kernel
> to control PDs when bound periphery is used.
> 
> If I understand bindings thing correctly we should make power-domains
> property required in bindings too in that case, at least for those
> peripheries which has *a1* compatibles (some peripheries use compatible
> from older SoCs without PDs).
> 
> What you think?

Yes, but if the compatible has already been defined without a required
power-domain, then it's too late to mark it as required since it's an ABI
break.

So next time a new compatible is added, it's the appropriate time to mark
it as required.

But in any case it's not a big deal because if the power-domain is not
specified it won't work, like if you use wrong register address or the
wrong interrupt line.

The fact power-domain can be specified is enough.

Neil

> 
> On 7/8/24 22:51, Krzysztof Kozlowski wrote:
>> On 08/07/2024 21:48, George Stark wrote:
>>> SPI Flash Controller has dedicated power domain so make the
>>> corresponding property required.
>>
>> That's an ABI break. Being part of power domain does not necessarily
>> mean it must be required, so your commit msg lacks rationale. Especially
>> on the ABI part.
>>
>>
>>
>> Best regards,
>> Krzysztof
>>
>