linux-kernel - Re: [Patch v4 0/6] Introduce LMh driver for Qualcomm SoCs

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Date:   Tue, 27 Jul 2021 12:44:20 -0500
From:   Steev Klimaszewski <steev@...i.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>, agross@...nel.org,
        bjorn.andersson@...aro.org, rui.zhang@...el.com,
        daniel.lezcano@...aro.org, viresh.kumar@...aro.org,
        rjw@...ysocki.net, robh+dt@...nel.org
Cc:     linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [Patch v4 0/6] Introduce LMh driver for Qualcomm SoCs


On 7/27/21 10:25 AM, Thara Gopinath wrote:
> Limits Management Hardware(LMh) is a hardware infrastructure on some
> Qualcomm SoCs that can enforce temperature and current limits as programmed
> by software for certain IPs like CPU. On many newer SoCs LMh is configured
> by firmware/TZ and no programming is needed from the kernel side. But on
> certain SoCs like sdm845 the firmware does not do a complete programming of
> the h/w block. On such SoCs kernel software has to explicitly set up the
> temperature limits and turn on various monitoring and enforcing algorithms
> on the hardware.
>
> Introduce support for enabling and programming various limit settings and
> monitoring capabilities of Limits Management Hardware(LMh) associated with
> cpu clusters. Also introduce support in cpufreq hardware driver to monitor
> the interrupt associated with cpu frequency throttling so that this
> information can be conveyed to the schdeuler via thermal pressure
> interface.
>
> With this patch series following cpu performance improvement(30-70%) is
> observed on sdm845. The reasoning here is that without LMh being programmed
> properly from the kernel, the default settings were enabling thermal
> mitigation for CPUs at too low a temperature (around 70-75 degree C).  This
> in turn meant that many a time CPUs were never actually allowed to hit the
> maximum possible/required frequencies.
>
> UnixBench whets and dhry (./Run whets dhry)
> System Benchmarks Index Score
>
>                 Without LMh Support             With LMh Support
> 1 copy test     1353.7                          1773.2
>
> 8 copy tests    4473.6                          7402.3
>
> Sysbench cpu
> sysbench cpu --threads=8 --time=60 --cpu-max-prime=100000 run
>
>                 Without LMh Support             With LMh Support
> Events per
> second                  355                             614
>
> Avg Latency(ms)         21.84                           13.02
>
> v3->v4:
> 	- Rebased to v5.14-rc2.
>
> v2->v3:
>         - Included patch adding dt binding documentation for LMh nodes.
>         - Rebased to v5.13
>
> Thara Gopinath (6):
>   firmware: qcom_scm: Introduce SCM calls to access LMh
>   thermal: qcom: Add support for LMh driver
>   cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support
>   arm64: dts: qcom: sdm45: Add support for LMh node
>   arm64: dts: qcom: sdm845: Remove cpufreq cooling devices for CPU
>     thermal zones
>   dt-bindings: thermal: Add dt binding for QCOM LMh
>
>  .../devicetree/bindings/thermal/qcom-lmh.yaml | 100 ++++++++
>  arch/arm64/boot/dts/qcom/sdm845.dtsi          | 162 ++----------
>  drivers/cpufreq/qcom-cpufreq-hw.c             | 142 +++++++++++
>  drivers/firmware/qcom_scm.c                   |  58 +++++
>  drivers/firmware/qcom_scm.h                   |   4 +
>  drivers/thermal/qcom/Kconfig                  |  10 +
>  drivers/thermal/qcom/Makefile                 |   1 +
>  drivers/thermal/qcom/lmh.c                    | 232 ++++++++++++++++++
>  include/linux/qcom_scm.h                      |  14 ++
>  9 files changed, 587 insertions(+), 136 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/thermal/qcom-lmh.yaml
>  create mode 100644 drivers/thermal/qcom/lmh.c
>
Tested-by: Steev Klimaszewski <steev@...i.org>