[Patch v3 0/6] Introduce LMh driver for Qualcomm SoCs

Thara Gopinath
2021-07-08T12:07:03Z

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

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: boot: dts: qcom: sdm45: Add support for LMh node
arm64: boot: 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 | 118 +++++++++
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 | 239 ++++++++++++++++++
include/linux/qcom_scm.h | 14 +
9 files changed, 570 insertions(+), 136 deletions(-)
create mode 100644 Documentation/devicetree/bindings/thermal/qcom-lmh.yaml
create mode 100644 drivers/thermal/qcom/lmh.c

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2.25.1