linux-kernel - [PATCH 0/2] PM: QoS/pmdomains: support resume latencies for system-wide PM

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Message-Id: <20260120-topic-lpm-pmdomain-device-constraints-v1-0-108fc4cfafce@baylibre.com>
Date: Tue, 20 Jan 2026 17:54:43 -0800
From: "Kevin Hilman (TI)" <khilman@...libre.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, 
 Ulf Hansson <ulf.hansson@...aro.org>, linux-pm@...r.kernel.org
Cc: Dhruva Gole <d-gole@...com>, linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] PM: QoS/pmdomains: support resume latencies for
 system-wide PM

Currently QoS resume latencies are only considered for runtime PM
transitions of pmdomains, which remains the default.

In order to also support QoS resume latencies during system-wide PM,
add a new flag to indicate a resume latency should be used for
system-wide PM *instead of* runtime PM.

For example, by doing this:

   # echo 500000 > /sys/devices/.../<dev0>/power/pm_qos_resume_latency_us

dev0 now has a resume latency of 500000 usec for runtime PM
transitions.

Then, if the new flag is also set:

   # echo 1 > /sys/devices/.../<dev0>/power/pm_qos_latency_sys

That 500000 usec delay now applies to system-wide PM (and not to
runtime PM).

If a user requires a different latency value for system-wide PM
compared to runtime PM, then the runtime PM value can be set for
normal operations, and the system-wide value (and flag) can be set by
userspace before suspend, and the runtime PM value can be restored
after resume.

To: Rafael J. Wysocki <rafael@...nel.org>
To: Ulf Hansson <ulf.hansson@...aro.org>
To: linux-pm@...r.kernel.org

Signed-off-by: Kevin Hilman (TI) <khilman@...libre.com>
---
Kevin Hilman (TI) (2):
      PM / QoS: add flag to indicate latency applies system-wide
      pmdommain: add support system-wide resume latency constraints

 drivers/base/power/sysfs.c  | 27 +++++++++++++++++++++++++++
 drivers/pmdomain/governor.c | 42 +++++++++++++++++++++++++++++++++++++++++-
 include/linux/pm_qos.h      |  2 ++
 3 files changed, 70 insertions(+), 1 deletion(-)
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20260120-topic-lpm-pmdomain-device-constraints-e5e78ce48502

Best regards,
--  
Kevin Hilman (TI) <khilman@...libre.com>