linux-kernel - Re: [PATCH v6 0/5] Add support for QCOM Core Power Reduction

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Message-ID: <CAPDyKFqjsJSRW7XvfUe2Ssewqxo5Xjk_3p_EywP_rTsvrdNDYQ@mail.gmail.com>
Date:   Wed, 20 Nov 2019 13:00:05 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Niklas Cassel <niklas.cassel@...aro.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Amit Kucheria <amit.kucheria@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6 0/5] Add support for QCOM Core Power Reduction

On Tue, 19 Nov 2019 at 16:46, Niklas Cassel <niklas.cassel@...aro.org> wrote:
>
> This series adds support for Core Power Reduction (CPR), a form of
> Adaptive Voltage Scaling (AVS), found on certain Qualcomm SoCs.
>
> This series is based on top of the qcs404 cpufreq patch series that
> hasn't landed yet:
> https://patchwork.kernel.org/project/linux-arm-msm/list/?series=173423
> as well as that series' matching device tree changes:
> https://patchwork.kernel.org/project/linux-arm-msm/list/?series=165457
>
> For testing purposes, this patch series, including the dependencies
> listed above, is available on the following git tag:
> https://git.linaro.org/people/niklas.cassel/kernel.git/log/?h=cpr-v6
>
> CPR is a technology that reduces core power on a CPU or on other device.
> It reads voltage settings from efuses (that have been written in
> production), it uses these voltage settings as initial values, for each
> OPP.
>
> After moving to a certain OPP, CPR monitors dynamic factors such as
> temperature, etc. and adjusts the voltage for that frequency accordingly
> to save power and meet silicon characteristic requirements.
>
> This driver has been developed together with Jorge Ramirez-Ortiz, and
> is based on an RFC by Stephen Boyd[1], which in turn is based on work
> by others on codeaurora.org[2].
>
> [1] https://lkml.org/lkml/2015/9/18/833
> [2] https://source.codeaurora.org/quic/la/kernel/msm-4.14/tree/drivers/regulator/cpr-regulator.c?h=msm-4.14
>
> Changes since v5:
> -Removed pm_ops from platform_driver struct.
>  (This was embarrassingly not properly removed in previous patch revision.)
>
> Niklas Cassel (5):
>   dt-bindings: power: avs: Add support for CPR (Core Power Reduction)
>   power: avs: Add support for CPR (Core Power Reduction)
>   arm64: dts: qcom: qcs404: Add CPR and populate OPP table
>   arm64: defconfig: enable CONFIG_QCOM_CPR
>   arm64: defconfig: enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM
>
>  .../bindings/power/avs/qcom,cpr.txt           |  130 ++
>  MAINTAINERS                                   |    8 +
>  arch/arm64/boot/dts/qcom/qcs404.dtsi          |  132 +-
>  arch/arm64/configs/defconfig                  |    2 +
>  drivers/power/avs/Kconfig                     |   15 +
>  drivers/power/avs/Makefile                    |    1 +
>  drivers/power/avs/qcom-cpr.c                  | 1754 +++++++++++++++++
>  7 files changed, 2034 insertions(+), 8 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/power/avs/qcom,cpr.txt
>  create mode 100644 drivers/power/avs/qcom-cpr.c
>
> --
> 2.23.0
>

For the series (except patch 2 that I provided some comment for), feel
free to add:

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Kind regards
Uffe