[PATCH v5 0/5] Add support for QCOM Core Power Reduction

[PATCH v5 0/5] Add support for QCOM Core Power Reduction

[Niklas Cassel]

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

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://www.codeaurora.org/cgit/quic/la/kernel/msm-3.10/tree/drivers/regulator/cpr-regulator.c?h=msm-3.10

Changes since V4:
Implemented review comments from Stephen Boyd.
Removed suspend()/resume(), since they did the same things as ->power_on()/
->power_off() genpd callbacks.

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                  | 1755 +++++++++++++++++
 7 files changed, 2035 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


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[PATCH v5 4/5] arm64: defconfig: enable CONFIG_QCOM_CPR

[Niklas Cassel]

Enable CONFIG_QCOM_CPR.

Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
---
 arch/arm64/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index e76b42b25dd6..4385033c0a34 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -438,6 +438,7 @@ CONFIG_GPIO_PCA953X=y
 CONFIG_GPIO_PCA953X_IRQ=y
 CONFIG_GPIO_MAX77620=y
 CONFIG_POWER_AVS=y
+CONFIG_QCOM_CPR=y
 CONFIG_ROCKCHIP_IODOMAIN=y
 CONFIG_POWER_RESET_MSM=y
 CONFIG_POWER_RESET_XGENE=y
-- 
2.23.0


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[PATCH v5 5/5] arm64: defconfig: enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM

[Niklas Cassel]

Enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM.

Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
---
 arch/arm64/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index 4385033c0a34..09aaffd473a0 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -88,6 +88,7 @@ CONFIG_ACPI_CPPC_CPUFREQ=m
 CONFIG_ARM_ARMADA_37XX_CPUFREQ=y
 CONFIG_ARM_SCPI_CPUFREQ=y
 CONFIG_ARM_IMX_CPUFREQ_DT=m
+CONFIG_ARM_QCOM_CPUFREQ_NVMEM=y
 CONFIG_ARM_QCOM_CPUFREQ_HW=y
 CONFIG_ARM_RASPBERRYPI_CPUFREQ=m
 CONFIG_ARM_TEGRA186_CPUFREQ=y
-- 
2.23.0


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Re: [PATCH v5 5/5] arm64: defconfig: enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM

[Stanimir Varbanov]

Hi Niklas,

On 11/15/19 2:15 PM, Niklas Cassel wrote:
> Enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM.

Shouldn't this be selected from qcom-cpr.c Kconfig ?

> 
> Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
> ---
>  arch/arm64/configs/defconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> index 4385033c0a34..09aaffd473a0 100644
> --- a/arch/arm64/configs/defconfig
> +++ b/arch/arm64/configs/defconfig
> @@ -88,6 +88,7 @@ CONFIG_ACPI_CPPC_CPUFREQ=m
>  CONFIG_ARM_ARMADA_37XX_CPUFREQ=y
>  CONFIG_ARM_SCPI_CPUFREQ=y
>  CONFIG_ARM_IMX_CPUFREQ_DT=m
> +CONFIG_ARM_QCOM_CPUFREQ_NVMEM=y
>  CONFIG_ARM_QCOM_CPUFREQ_HW=y
>  CONFIG_ARM_RASPBERRYPI_CPUFREQ=m
>  CONFIG_ARM_TEGRA186_CPUFREQ=y
> 

-- 
regards,
Stan

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Re: [PATCH v5 5/5] arm64: defconfig: enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM

[Niklas Cassel]

On Fri, Nov 15, 2019 at 02:44:03PM +0200, Stanimir Varbanov wrote:
> Hi Niklas,
> 
> On 11/15/19 2:15 PM, Niklas Cassel wrote:
> > Enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM.
> 
> Shouldn't this be selected from qcom-cpr.c Kconfig ?

Hello Stan,

I can see where this is coming from.

If e.g. CONFIG_ARM_QCOM_CPUFREQ_NVMEM is selected but
CONFIG_QCOM_CPR is not, then the cpufreq driver will
return -EPROBE_DEFER, and will never probe successfully.

However, I don't really see a difference to any other
driver using a framework that the user has not enabled.
The driver will then use that framework's stubs, which
usually only return -ENODEV or similar.

So even though these both need to be enabled to work as
intended, they can be compiled/build tested separately.


Kind regards,
Niklas

> 
> > 
> > Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
> > ---
> >  arch/arm64/configs/defconfig | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> > index 4385033c0a34..09aaffd473a0 100644
> > --- a/arch/arm64/configs/defconfig
> > +++ b/arch/arm64/configs/defconfig
> > @@ -88,6 +88,7 @@ CONFIG_ACPI_CPPC_CPUFREQ=m
> >  CONFIG_ARM_ARMADA_37XX_CPUFREQ=y
> >  CONFIG_ARM_SCPI_CPUFREQ=y
> >  CONFIG_ARM_IMX_CPUFREQ_DT=m
> > +CONFIG_ARM_QCOM_CPUFREQ_NVMEM=y
> >  CONFIG_ARM_QCOM_CPUFREQ_HW=y
> >  CONFIG_ARM_RASPBERRYPI_CPUFREQ=m
> >  CONFIG_ARM_TEGRA186_CPUFREQ=y
> > 
> 
> -- 
> regards,
> Stan

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