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    SubjectRe: [PATCH v4 1/4] dt-bindings: interconnect: qcom,sdm845-cpu-bwmon: add BWMON device
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    On 22/06/2022 13:58, Rajendra Nayak wrote:
    >
    >
    > On 6/7/2022 12:20 PM, Krzysztof Kozlowski wrote:
    >> On 06/06/2022 23:11, Bjorn Andersson wrote:
    >>> On Wed 01 Jun 03:11 PDT 2022, Krzysztof Kozlowski wrote:
    >>>
    >>>> Add bindings for the Qualcomm Bandwidth Monitor device providing
    >>>> performance data on interconnects. The bindings describe only BWMON
    >>>> version 4, e.g. the instance on SDM845 between CPU and Last Level Cache
    >>>> Controller.
    >>>>
    >>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
    >>>> Reviewed-by: Rob Herring <robh@kernel.org>
    >>>> Acked-by: Georgi Djakov <djakov@kernel.org>
    >>>> ---
    >>>> .../interconnect/qcom,sdm845-cpu-bwmon.yaml | 97 +++++++++++++++++++
    >>>> 1 file changed, 97 insertions(+)
    >>>> create mode 100644 Documentation/devicetree/bindings/interconnect/qcom,sdm845-cpu-bwmon.yaml
    >>>>
    >>>> diff --git a/Documentation/devicetree/bindings/interconnect/qcom,sdm845-cpu-bwmon.yaml b/Documentation/devicetree/bindings/interconnect/qcom,sdm845-cpu-bwmon.yaml
    >>>> new file mode 100644
    >>>> index 000000000000..8c82e06ee432
    >>>> --- /dev/null
    >>>> +++ b/Documentation/devicetree/bindings/interconnect/qcom,sdm845-cpu-bwmon.yaml
    >>>> @@ -0,0 +1,97 @@
    >>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
    >>>> +%YAML 1.2
    >>>> +---
    >>>> +$id: http://devicetree.org/schemas/interconnect/qcom,sdm845-cpu-bwmon.yaml#
    >>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
    >>>> +
    >>>> +title: Qualcomm Interconnect Bandwidth Monitor
    >>>> +
    >>>> +maintainers:
    >>>> + - Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
    >>>> +
    >>>> +description:
    >>>> + Bandwidth Monitor measures current throughput on buses between various NoC
    >>>> + fabrics and provides information when it crosses configured thresholds.
    >>>> +
    >>>> +properties:
    >>>> + compatible:
    >>>> + enum:
    >>>> + - qcom,sdm845-cpu-bwmon # BWMON v4
    >>>
    >>> It seems the thing that's called bwmon v4 is compatible with a number of
    >>> different platforms, should we add a generic compatible to the binding
    >>> as well, to avoid having to update the implementation for each SoC?
    >>>
    >>> (I.e. "qcom,sdm845-cpu-bwmon", "qcom,bwmon-v4")
    >
    > it seems pretty useful to have the "qcom,bwmon-v4" and "qcom,bwmon-v5"
    > compatibles, I tried these patches on a sc7280 device which has a bwmon4
    > between the cpu and caches (and also has a bwmon5 between the caches and DDR)
    > and the driver works with zero changes.

    The trouble with naming it v4 is that such versioning does not exist in
    documentation. At least I failed to find it. Neither there is clear
    mapping between SoC and block version.

    The only indication about BWMON versioning comes from downstream
    sources, which I find not enough to justify usage of versions for blocks.

    Therefore as per DT recommendation (which I am enforcing on others) I am
    not planning put there bwmon-v4.

    Best regards,
    Krzysztof

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