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From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date:   Wed, 5 Oct 2022 00:05:07 +0300
Message-ID: <CAA8EJpoqKCj4tyX-617YJH5zqkR_C=1LVMeLXcCxZFgOPjRZ=g@mail.gmail.com>
Subject: Re: [PATCH 1/5] dt-bindings: firmware: scm: Add QDU1000/QRU1000 compatibles
To:     Melody Olvera <quic_molvera@quicinc.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Bhupesh Sharma <bhupesh.sharma@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-mmc@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, 4 Oct 2022 at 18:52, Melody Olvera <quic_molvera@quicinc.com> wrote=
:
>
>
> On 10/4/2022 2:36 AM, Dmitry Baryshkov wrote:
> > On Tue, 4 Oct 2022 at 09:53, Krzysztof Kozlowski
> > <krzysztof.kozlowski@linaro.org> wrote:
> >> On 04/10/2022 00:14, Dmitry Baryshkov wrote:
> >>> On Tue, 4 Oct 2022 at 01:02, Melody Olvera <quic_molvera@quicinc.com>=
 wrote:
> >>>>
> >>>> On 10/1/2022 4:25 AM, Krzysztof Kozlowski wrote:
> >>>>> On 01/10/2022 05:06, Melody Olvera wrote:
> >>>>>> Add compatibles for scm driver for QDU1000 and QRU1000 platforms.
> >>>>>>
> >>>>>> Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
> >>>>>> ---
> >>>>>>  Documentation/devicetree/bindings/firmware/qcom,scm.yaml | 2 ++
> >>>>>>  1 file changed, 2 insertions(+)
> >>>>>>
> >>>>>> diff --git a/Documentation/devicetree/bindings/firmware/qcom,scm.y=
aml b/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
> >>>>>> index c5b76c9f7ad0..b47a5dda3c3e 100644
> >>>>>> --- a/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
> >>>>>> +++ b/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
> >>>>>> @@ -51,6 +51,8 @@ properties:
> >>>>>>            - qcom,scm-sm8250
> >>>>>>            - qcom,scm-sm8350
> >>>>>>            - qcom,scm-sm8450
> >>>>>> +          - qcom,scm-qdu1000
> >>>>>> +          - qcom,scm-qru1000
> >>> I think after seeing all the patchsets it's time to ask the following
> >>> question. Do we really need a duplicate compatibility families:
> >>> qdu1000 vs qru1000? I'd suggest using a single set of compatibile
> >>> strings in most of the cases.
> >>> Settle down onto a single name (qdu,qru, qdru, whatever) and define
> >>> distinct compat strings only when there is an actual difference?
> >>>
> >>> E.g .we don't have separate compatible strings for all the sda660,
> >>> apq8096, etc. unless this is required by the corresponding hardware
> >>> block not being compatible with corresponding sdm or msm counterpart.
> >>>
> >> I am not that fluent in Qualcomm naming, so let me ask - what are the
> >> differences between QDU and QRU?
> >>
> >> For compatible (and/or similar) devices the general recommendation is =
to
> >> have specific compatibles followed by fallback. Even if devices are
> >> very, very, very similar, usually the recommendation still stays.
> > Well, true. But in some cases we handle this by using a single set of
> > compatibles. Consider e.g. sa8155 vs sm8150 (sa8155 overrides just few
> > compats that differ). Or qrb5165 vs sm8250 (there is no separate
> > qrb5165.dtsi). APQ8096 (#include "msm8996.dtsi"). Etc.
> >
> > I'd say this really depends on the actual difference between qru and qd=
u.
>
> To add some clarification, there's pretty little functional difference be=
tween the QDU (Distributed Unit) and the QRU (Radio Unit); they're largely =
the same SoC from the kernel's standpoint. I wasn't sure if it made more se=
nse to separate the compat strings or mash them together (using qdru to spe=
cify that it applies to both), so I kept separate compat strings in case th=
ere was a separate RU/DU use case down the line and also to avoid some conf=
usion (I guess that didn't work though). It makes the most sense in my mind=
 to just use the qdru compat string for the things that apply to both SoCs =
(which is most of what's submitted currently) and then we can do qdu/qru sp=
ecific override strings for more specific drivers.

Unless Krzysztof or Bjorn have other opinion, I'd suggest adding a
single compat string, It might be qcom,qdru1000-foo or just
qcom,qdu1000-foo (with having a separate qcom,qru1000-foo where
applicable). But the final decision is from Rob, Krzysztof and Bjorn.

--=20
With best wishes
Dmitry