linux-kernel - [PATCH v2 0/2] Enable CPU Idle for gs101

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Message-Id: <20250611-gs101-cpuidle-v2-0-4fa811ec404d@linaro.org>
Date: Wed, 11 Jun 2025 10:34:24 +0100
From: Peter Griffin <peter.griffin@...aro.org>
To: André Draszik <andre.draszik@...aro.org>, 
 Tudor Ambarus <tudor.ambarus@...aro.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
 Krzysztof Kozlowski <krzk@...nel.org>
Cc: William Mcvicker <willmcvicker@...gle.com>, 
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, 
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 kernel-team@...roid.com, Peter Griffin <peter.griffin@...aro.org>, 
 Will Deacon <willdeacon@...gle.com>, 
 Youngmin Nam <youngmin.nam@...sung.com>
Subject: [PATCH v2 0/2] Enable CPU Idle for gs101

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@...aro.org>
---
Changes in v2:
 * rebase onto next-20250610
 * Add #ifdef CONFIG_PM_SLEEP to avoid
   Fix warning: unused variable 'cpupm_pm_ops' [-Wunused-const-variable] (0-day)
- Link to v1: https://lore.kernel.org/r/20250524-gs101-cpuidle-v1-0-aea77a7842a6@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             | 137 ++++++++++++++++++++++++++-
 2 files changed, 136 insertions(+), 4 deletions(-)
---
base-commit: b27cc623e01be9de1580eaa913508b237a7a9673
change-id: 20250524-gs101-cpuidle-cafc96dd849d

Best regards,
-- 
Peter Griffin <peter.griffin@...aro.org>