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[0/2] Enable CPU Idle for gs101

Message ID 20250524-gs101-cpuidle-v1-0-aea77a7842a6@linaro.org
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Series Enable CPU Idle for gs101 | expand

Message

Peter Griffin May 24, 2025, 7:30 a.m. UTC 
Hi folks,

This series adds support for CPU Idle on gs101. In particular it
achieves this by registerring a cpu pm notifier and programming
a ACPM hint to enter the c2 idle state. With the hint programmed
the system now enters c2 idle state.

Note: the driver patch has a runtime dependency on the device tree
change to add `local-timer-stop` DT property to the CPU nodes.
Without this DT patch the system will hang in early boot as the
local timer is shutdown. The DT patch was originally sent along
with Wills MCT series in [1] but it can be merged independently
of the rest of the MCT changes, so I've included it here to
(hopefully!) make things clearer and easier as it has a strong
dependency with this patch.

We can measure the impact of these changes upstream using the fuel
gauge series from Thomas Antoine [2]. With the ACPM hint now
programmed /sys/class/power_supply/max77759-fg/current_avg is a
postive number around 150000 microamps meaning we are charging the
battery (assuming it isn't already full).

Prior to programming the hint this would report a negative number
around -150000 microamps meaning the battery was discharing.

Thanks,

Peter

[1] https://lore.kernel.org/lkml/20250402233407.2452429-5-willmcvicker@google.com/
[2] https://lore.kernel.org/lkml/20250421-b4-gs101_max77759_fg-v3-0-50cd8caf9017@uclouvain.be/

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
---
Peter Griffin (1):
      soc: samsung: exynos-pmu: Enable CPU Idle for gs101

Will Deacon (1):
      arm64: dts: exynos: gs101: Add 'local-timer-stop' to cpuidle nodes

 arch/arm64/boot/dts/exynos/google/gs101.dtsi |   3 +
 drivers/soc/samsung/exynos-pmu.c             | 135 ++++++++++++++++++++++++++-
 2 files changed, 134 insertions(+), 4 deletions(-)
---
base-commit: 176e917e010cb7dcc605f11d2bc33f304292482b
change-id: 20250524-gs101-cpuidle-cafc96dd849d

Best regards,