Re: [PATCH 2/5] clk: qcom: apcs-msm8916: get parent clock names from DT

Jorge Ramirez
2019-09-10T09:34:52Z

On 9/10/19 11:14, Stephen Boyd wrote:
> Quoting Jorge Ramirez-Ortiz, Linaro (2019-09-09 09:54:08)
>> On 09/09/19 09:17:03, Stephen Boyd wrote:
>>> But now the binding is different for the same compatible. I'd prefer we
>>> keep using devm_clk_get() and use a device pointer here and reorder the
>>> map and parent arrays instead. The clocks property shouldn't change in a
>>> way that isn't "additive" so that we maintain backwards compatibility.
>>>
>>
>> but the backwards compatibility is fully maintained - that is the main reason
>> behind the change. the new stuff is that instead of hardcoding the
>> names in the source - like it is being done on the msm8916- we provide
>> the clocks in the dts node (a cleaner approach with the obvious
>> benefit of allowing new users to be added without having to modify the
>> sources).
>>
>
> This is not a backwards compatible change.
>
>>>> --- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
>>>> @@ -429,7 +429,8 @@
>>>> compatible = "qcom,msm8916-apcs-kpss-global", "syscon";
>>>> reg = <0xb011000 0x1000>;
>>>> #mbox-cells = <1>;
>>>> - clocks = <&a53pll>;
>>>> + clocks = <&gcc GPLL0_VOTE>, <&a53pll>;
>>>> + clock-names = "aux", "pll";
>>>> #clock-cells = <0>;
>>>> };
>>>>
>
> Because the "clocks" property changed from
>
> <&a53pll>
>
> to
>
> <&gcc GPLL0_VOTE>, <&a53pll>
>
> and that moves pll to cell 1 instead of cell 0.
>
>

what do you mean by backwards compatible? because this change does not
break previous clients.