[RFC 0/7] cpuidle: Add poking mechanism to support non-IPI wakeup

Abel Vesa
2019-03-27T13:21:11Z

This work is a workaround I'm looking into (more as a background task)
in order to add support for cpuidle on i.MX8MQ based platforms.

The main idea here is getting around the missing GIC wake_request signal
(due to integration design issue) by waking up a each individual core through
some dedicated SW power-up bits inside the power controller (GPC) right before
every IPI is requested for that each individual core.

This work is basically composed of four parts (in kernel):

- the cpuidle core poking mechanism along with the related sched/irq_work calls
- the cpuidle-arm ops addition in order to support poking, along with the
'local-wakeup-poke' DT idle state knob
- the psci and cpu_ops cpu_poke addition
- the i.MX8MQ specific idle states in dts

There is also a change needed in TF-A which is available here:

https://lists.trustedfirmware.org/pipermail/tf-a/2019-March/000009.html

Abel Vesa (7):
sched: idle: Add sched get idle state helper
cpuidle: Add cpu poke support
smp: Poke the cores before requesting IPI
psci: Add cpu_poke ops to support core poking
cpuidle-arm: Add ops to support poke alonside enter
cpuidle-arm: Add arm64 wake helper for cpu_poke op
arm64: dts: imx8mq: Add cpu-sleep state with poke wake-up enabled

arch/arm64/boot/dts/freescale/imx8mq.dtsi | 20 ++++++++++++++++++
arch/arm64/include/asm/cpu_ops.h | 1 +
arch/arm64/include/asm/cpuidle.h | 6 ++++++
arch/arm64/kernel/cpuidle.c | 8 ++++++++
arch/arm64/kernel/psci.c | 1 +
drivers/cpuidle/cpuidle-arm.c | 13 +++++++++++-
drivers/cpuidle/cpuidle.c | 34 +++++++++++++++++++++++++++++++
drivers/cpuidle/dt_idle_states.c | 15 +++++++++-----
drivers/cpuidle/dt_idle_states.h | 10 +++++++++
drivers/firmware/psci.c | 6 ++++++
include/linux/cpuidle.h | 7 +++++++
include/linux/psci.h | 1 +
include/uapi/linux/psci.h | 2 ++
kernel/irq_work.c | 19 ++++++++++++++---
kernel/sched/core.c | 16 ++++++++++-----
kernel/sched/idle.c | 11 ++++++++++
kernel/smp.c | 10 ++++++++-
kernel/time/tick-broadcast.c | 4 ++++
18 files changed, 169 insertions(+), 15 deletions(-)

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2.7.4