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621a88dbfe
Currently cpu hotplug with the PREEMPT_RT option set in the kernel is
not supported because the underlying generic power domain functions
used in the cpu hotplug callbacks are incompatible from a lock point
of view. This situation prevents the suspend to idle to reach the
deepest idle state for the "cluster" as identified in the
undermentioned commit.
Use the compatible ones when PREEMPT_RT is enabled and remove the
boolean disabling the hotplug callbacks with this option.
With this change the platform can reach the deepest idle state
allowing at suspend time to consume less power.
Tested-on Lenovo T14s with the following script:
echo 0 > /sys/devices/system/cpu/cpu3/online
BEFORE=$(cat /sys/kernel/debug/pm_genpd/power-domain-cpu-cluster0/idle_states | grep S0 | awk '{ print $3 }') ;
rtcwake -s 1 -m mem;
AFTER=$(cat /sys/kernel/debug/pm_genpd/power-domain-cpu-cluster0/idle_states | grep S0 | awk '{ print $3 }');
if [ $BEFORE -lt $AFTER ]; then
echo "Test successful"
else
echo "Test failed"
fi
echo 1 > /sys/devices/system/cpu/cpu3/online
Fixes: 1c4b2932bd ("cpuidle: psci: Enable the hierarchical topology for s2idle on PREEMPT_RT")
Cc: Raghavendra Kakarla <quic_rkakarla@quicinc.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250709154728.733920-1-daniel.lezcano@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.