Re: [RFC PATCH 6/6] arm64: dts: qcom: sc7180: Add SoC specific compatible to soc node

Konrad Dybcio
2025-01-09T14:10:38Z

On 8.01.2025 2:02 PM, Dmitry Baryshkov wrote:
> On Tue, Jan 07, 2025 at 05:28:43PM -0800, Stephen Boyd wrote:
>> Allow an SoC driver to probe for these devices. Add the SoC specific
>> compatible to the soc node. Leave the original simple-bus compatible in
>> place so that everything keeps working.
>>
>> Cc: Rob Herring <robh@kernel.org>
>> Cc: Bjorn Andersson <andersson@kernel.org>
>> Cc: Konrad Dybcio <konradybcio@kernel.org>
>> Cc: <linux-arm-msm@vger.kernel.org>
>> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
>> ---
>> arch/arm64/boot/dts/qcom/sc7180.dtsi | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi
>> index 76fe314d2ad5..257890a193e6 100644
>> --- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
>> @@ -782,7 +782,7 @@ soc: soc@0 {
>> #size-cells = <2>;
>> ranges = <0 0 0 0 0x10 0>;
>> dma-ranges = <0 0 0 0 0x10 0>;
>> - compatible = "simple-bus";
>> + compatible = "qcom,soc-sc7180", "simple-bus";
>
> If the new driver requires this compatible, it will break compatibility
> with older DT files (and it should be avoided).

IIUC the intent here is to provide backwards compatibility through checking
for sth like IS_SOCPM_MANAGED(), sorta like HAS_ACPI_COMPANION(). In that
case, power sequencing would be done by the socpm driver, whereas if it
doesn't hold, the resources would be toggled by the device driver

Konrad