linux-kernel - [PATCH v2 0/4] PM: QoS: Introduce a CPU system-wakeup QoS limit for s2idle

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Message-ID: <20251016151929.75863-1-ulf.hansson@linaro.org>
Date: Thu, 16 Oct 2025 17:19:20 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: "Rafael J . Wysocki" <rafael@...nel.org>,
	linux-pm@...r.kernel.org
Cc: Vincent Guittot <vincent.guittot@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Kevin Hilman <khilman@...libre.com>,
	Pavel Machek <pavel@...nel.org>,
	Len Brown <len.brown@...el.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Maulik Shah <quic_mkshah@...cinc.com>,
	Prasad Sodagudi <psodagud@...cinc.com>,
	Dhruva Gole <d-gole@...com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/4] PM: QoS: Introduce a CPU system-wakeup QoS limit for s2idle

Changes in v2:
	- Limit the new QoS to CPUs  and make some corresponding renaming of the
	functions along with name of the device node for user space.
	- Make sure we deal with the failure/error path correctly when there are
	no state available for s2idle.
	- Add documentation.

Some platforms supports multiple low-power states for CPUs that can be used
when entering system-wide suspend and s2idle in particular. Currently we are
always selecting the deepest possible state for the CPUs, which can break the
system-wakeup latency constraint that may be required for some use-cases.

Therefore, this series suggests to introduce a new interface for user-space,
allowing us to specify the CPU system-wakeup QoS limit. The QoS limit is then
taken into account when selecting a suitable low-power state for s2idle.

Kind regards
Ulf Hansson


Ulf Hansson (4):
  PM: QoS: Introduce a CPU system-wakeup QoS limit
  pmdomain: Respect the CPU system-wakeup QoS limit during s2idle
  sched: idle: Respect the CPU system-wakeup QoS limit for s2idle
  Documentation: power/cpuidle: Document the CPU system-wakeup latency
    QoS

 Documentation/admin-guide/pm/cpuidle.rst |   7 ++
 Documentation/power/pm_qos_interface.rst |   9 +-
 drivers/cpuidle/cpuidle.c                |  12 +--
 drivers/pmdomain/core.c                  |  10 ++-
 drivers/pmdomain/governor.c              |  27 ++++++
 include/linux/cpuidle.h                  |   6 +-
 include/linux/pm_domain.h                |   1 +
 include/linux/pm_qos.h                   |   5 ++
 kernel/power/qos.c                       | 102 +++++++++++++++++++++++
 kernel/sched/idle.c                      |  12 +--
 10 files changed, 173 insertions(+), 18 deletions(-)

-- 
2.43.0