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

From: Steev Klimaszewski
Date: Tue Jul 27 2021 - 13:44:29 EST



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@xxxxxxxx>