On Fri, Mar 01, 2024 at 12:53:25PM +0100, Ulf Hansson wrote: > On Wed, 28 Feb 2024 at 18:11, Srinivas Kandagatla > <srinivas.kandagatla@xxxxxxxxxx> wrote: > > > > > > > > On 28/02/2024 16:22, Ulf Hansson wrote: > > > On Wed, 28 Feb 2024 at 17:09, Sudeep Holla <sudeep.holla@xxxxxxx> wrote: > > >> > > >> On Wed, Feb 28, 2024 at 03:20:44PM +0100, Krzysztof Kozlowski wrote: > > >>> On 28/02/2024 15:02, Sudeep Holla wrote: > > >>>> On Wed, Feb 28, 2024 at 02:27:30PM +0100, Ulf Hansson wrote: > > >>>>> On Mon, 26 Feb 2024 at 15:24, Nikunj Kela <quic_nkela@xxxxxxxxxxx> wrote: > > >>>>>> > > >>>>>> Hi Sudeep, > > >>>>>> > > >>>>>> I would like to conclude on this thread. I was discussing this with Ulf. > > >>>>>> He thinks that using the domain names to identify if platform is > > >>>>>> abstracting clocks etc. are not scalable and sufficient. Instead he > > >>>>>> thinks that the change in the interface to OS(and FW) is a good > > >>>>>> candidate for a new compatible(even though HW is same). Even for SCMI, > > >>>>>> we do change phandle in DT to SCMI protocol phandle so that is like a > > >>>>>> different platform altogether. Could you please let me know if you still > > >>>>>> think that using a different compatible in this case is not warranted. > > >>>>> > > >>>>> My apologies for joining this discussion at this late state. Yet, I > > >>>>> just wanted to confirm what Nikunj said above. > > >>>>> > > >>>>> In the end we are indeed talking about adding a new platform, as > > >>>>> changing the FW interface from a QCOM proprietary one into SCMI, > > >>>>> simply requires updates to a DTS file(s) that is platform specific. > > >>>>> > > >>>> > > >>>> The way I read this sounds like all this are platform specific and need > > >>>> new compatible. > > >>>> > > >>>>> That said, it also seems reasonable to me to use a compatible string, > > >>>>> to allow us to describe the update of HW for various affected devices. > > >>>>> > > >>>> > > >>>> While I agree with the above statement, it depends on what you refer as > > >>>> update of HW above. It is all Qcom specific and there is so much turn > > >>>> between SoCs that this shouldn't matter but I would like to take example > > >>>> and describe what I initially mentioned/argued against. > > >>>> > > >>>> Lets us assume 2 SoCs: A and B. A is old and didn't use SCMI while B is > > >>>> new and migrated to use SCMI. Now let us assume both A and B SoCs have > > >>>> exact same version/revision of an IP: X. Now just because B uses SCMI, > > >>>> should X have one compatible to be used in A and another in B. That > > >>>> doesn't sound right IMO. > > >>> > > >>> That's trivial to answer, because these are different SoCs. Compatibles > > >>> are SoC specific and every SoC-IP-block needs its compatible. Rob was > > >>> repeating this many times that versioned compatibles are discouraged. > > >> > > >> OK I may have confused or derailed the discussion with the mention of > > >> "exact same version/revision" of X. This is not related versioned compatibles. > > >> Let me try to explain it with some real example. If you look at all the > > >> users of "arm,coresight-tpiu", they all have same compatible on all the > > >> platforms irrespective of the clock/reset/voltage/power domain providers > > >> on these platforms. > > >> > > >> E.g. on juno it is based on SCMI while on qcom-msm8974/apq8064 or > > >> hi3660/hi6220 it is platform specific clock/power domain providers. > > >> However all these platform have the same compatible "arm,coresight-tpiu". > > >> That was the point I was trying to make and not related to versioned > > >> compatible for different versions on an IP. > > > > > > That's perfectly fine, if that is sufficient. It would also be > > > perfectly fine to extend it with a platform/soc specific compatible, > > > when needed. > > > > > > An example could be: > > > compatible = "qcom,sm8450-coresight-tpiu", "arm,coresight-tpiu"; > > > > The issue is not the same as the above example. > > > > We already have a soc specific compatible in this case > > ex: "qcom,sc8280xp-ufshc" > > > > making another compatible like "qcom,sc8280xp-ufshc-scmi" or > > "qcom,sc8280xp-ufshc-xyz" based on how some of the resources (clks, > > regulators) are provided in bindings does not really make sense. > > > > Fact is that we are representing the same IP block. > > > > AFAIU, we should go with same compatible irrespective of how the > > resourcing needs are satisfied. > > I get your point. Nevertheless, we need to create a new platform (new > DTS file), as we are changing the FW interface to SCMI. That means the > toplevel compatible for the platform will be a new one > (Documentation/devicetree/bindings/arm/qcom.yaml). > While I don't understand the details of the above mentioned platform, it should be a blanket rule that the toplevel compatible for the platform has to be new. Check arch/arm64/boot/dts/arm/juno.dts arch/arm64/boot/dts/arm/juno-scmi.dtsi arch/arm64/boot/dts/arm/juno-scmi.dts One is with old firmware interface and -scmi is with SCMI. No new top level compatible change is needed. I understand it was switch from one interface to the another and not like Qcom platforms which is moving from in-kernel solution to firmware solution. But the general rule applies here as well unless there are specific reasons for needing that exception. I am not against it or ruling that out, just curious to understand them. -- Regards, Sudeep
