linux-kernel - Re: [PATCH v11 1/5] dt-bindings: Introduce QCOM Sleep stats bindings

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Date:   Thu, 7 Oct 2021 21:50:40 +0200
From:   Stephan Gerhold <stephan@...hold.net>
To:     Maulik Shah <mkshah@...eaurora.org>
Cc:     swboyd@...omium.org, mka@...omium.org, evgreen@...omium.org,
        bjorn.andersson@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, agross@...nel.org,
        dianders@...omium.org, linux@...ck-us.net, rnayak@...eaurora.org,
        lsrao@...eaurora.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v11 1/5] dt-bindings: Introduce QCOM Sleep stats bindings

On Thu, Oct 07, 2021 at 03:27:25PM +0530, Maulik Shah wrote:
> From: Mahesh Sivasubramanian <msivasub@...eaurora.org>
> 
> Add device binding documentation for Qualcomm Technologies, Inc. (QTI)
> Sleep stats driver. The driver is used for displaying Sleep statistic maintained
> by Always On Processor or Resource Power Manager.
> 
> Cc: devicetree@...r.kernel.org
> Signed-off-by: Mahesh Sivasubramanian <msivasub@...eaurora.org>
> Signed-off-by: Lina Iyer <ilina@...eaurora.org>
> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
> Reviewed-by: Rob Herring <robh@...nel.org>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> ---
>  .../bindings/soc/qcom/qcom-sleep-stats.yaml        | 47 ++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
> 
> diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
> new file mode 100644
> index 0000000..5213daf
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
> @@ -0,0 +1,47 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/soc/qcom/qcom-sleep-stats.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm Technologies, Inc. (QTI) Sleep stats bindings
> +
> +maintainers:
> +  - Maulik Shah <mkshah@...eaurora.org>
> +
> +description:
> +  Always On Processor/Resource Power Manager maintains statistics of the SoC
> +  sleep modes involving powering down of the rails and oscillator clock.
> +
> +  Statistics includes SoC sleep mode type, number of times low power mode were
> +  entered, time of last entry, time of last exit and accumulated sleep duration.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - qcom,rpmh-sleep-stats
> +      - qcom,rpm-sleep-stats
> +
> +  reg:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  # Example of rpmh sleep stats
> +  - |
> +    sram@...0000 {
> +      compatible = "qcom,rpmh-sleep-stats";
> +      reg = <0x0c3f0000 0x400>;
> +    };
> +  # Example of rpm sleep stats
> +  - |
> +    sram@...0000 {
> +      compatible = "qcom,rpm-sleep-stats";
> +      reg = <0x04690000 0x400>;
> +    };

Does this region really only contain "rpm-*sleep*-stats"? AFAICT this is
really a more generic memory region where various offsets are read from.

These are all the offsets in msm8998-pm.dtsi downstream [1]:
  ...9000c: rpm-rail-stats offset
  ...90014: rpm-sleep-stats offset (RPM_DYNAMIC_ADDR in your driver)
  ...90018: rpm-log offset
  ...9001c: "RPM FREE HEAP SPACE"

How would you set up any of the other drivers if the entire region
is declared as "rpm-sleep-stats"?

Perhaps this region should have a more generic name that represents what
it actually is and not only one of the information it contains, similar
to "qcom,rpm-msg-ram"?

Thanks,
Stephan

[1]: https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/arch/arm/boot/dts/qcom/msm8998-pm.dtsi?h=LA.UM.8.4.1.c25#n271