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

From: neil . armstrong
Date: Wed Jul 10 2024 - 12:41:06 EST


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