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(-) -- 2.7.4
