Rafael, Sudeep, Lorenzo, Mark, On Thu, 29 Nov 2018 at 18:47, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > Over the years this series have been iterated and discussed at various Linux > conferences and LKML. In this new v10, a quite significant amount of changes > have been made to address comments from v8 and v9. A summary is available > below, although let's start with a brand new clarification of the motivation > behind this series. > > For ARM64/ARM based platforms CPUs are often arranged in a hierarchical manner. > From a CPU idle state perspective, this means some states may be shared among a > group of CPUs (aka CPU cluster). > > To deal with idle management of a group of CPUs, sometimes the kernel needs to > be involved to manage the last-man standing algorithm, simply because it can't > rely solely on power management FWs to deal with this. Depending on the > platform, of course. > > There are a couple of typical scenarios for when the kernel needs to be in > control, dealing with synchronization of when the last CPU in a cluster is about > to enter a deep idle state. > > 1) > The kernel needs to carry out so called last-man activities before the > CPU cluster can enter a deep idle state. This may for example involve to > configure external logics for wakeups, as the GIC may no longer be functional > once a deep cluster idle state have been entered. Likewise, these operations > may need to be restored, when the first CPU wakes up. > > 2) > Other more generic I/O devices, such as an MMC controller for example, may be a > part of the same power domain as the CPU cluster, due to a shared power-rail. > For these scenarios, when the MMC controller is in use dealing with an MMC > request, a deeper idle state of the CPU cluster may needs to be temporarily > disabled. This is needed to retain the MMC controller in a functional state, > else it may loose its register-context in the middle of serving a request. > > In this series, we are extending the generic PM domain (aka genpd) to be used > for also CPU devices. Hence the goal is to re-use much of its current code to > help us manage the last-man standing synchronization. Moreover, as we already > use genpd to model power domains for generic I/O devices, both 1) and 2) can be > address with its help. > > Moreover, to address these problems for ARM64 DT based platforms, we are > deploying support for genpd and runtime PM to the PSCI FW driver - and finally > we make some updates to two ARM64 DTBs, as to deploy the new PSCI CPU topology > layout. > > The series has been tested on the QCOM 410c dragonboard and the Hisilicon Hikey > board. You may also find the code at: > > git.linaro.org/people/ulf.hansson/linux-pm.git next It's soon been three weeks since I posted this and I would really appreciate some feedback. Rafael, I need your feedback on patch 1->4. Mark, Sudeep, Lorenzo, please have a look at the PSCI related changes. When it comes to the the cpuidle related changes, I have pinged Daniel offlist - and he is preparing some responses. Kind regards Uffe > > Kind regards > Ulf Hansson > > > Changes in v10: > - Quite significant changes have been to the PSCI driver deployment. According > to an agreement with Lorenzo, the hierarchical CPU layout for PSCI should be > orthogonal to whether the PSCI FW supports OSI or not. This has been taken > care of in this version. > - Drop the generic attach/detach helpers of CPUs to genpd, instead make that > related code internal to PSCI, for now. > - Fix "BUG: sleeping for invalid context" for hotplug, as reported by Raju. > - Addressed various comments from version 8 and 9. > - Clarified changelogs and re-wrote the cover-letter to better explain the > motivations behind these changes. > > Changes in v9: > - Collect only a subset from the changes in v8. > - Patch 3 is new, documenting existing genpd flags. Future wise, this means > when a new genpd flag is invented, we must also properly document it. > - No changes have been made to the patches picked from v8. > - Dropped the text from v8 cover-letter[1], to avoid confusion. When posting v10 > (or whatever the next version containing the rest becomes), I am going re-write > the cover-letter to clarify, more exactly, the problems this series intends to > solve. The earlier text was simply too vague. > > [1] > https://lwn.net/Articles/758091/ > > Changes in v8: > - Added some tags for reviews and acks. > - Cleanup timer patch (patch6) according to comments from Rafael. > - Rebased series on top of v4.18rc1 - it applied cleanly, except for patch 5. > - While adopting patch 5 to new genpd changes, I took the opportunity to > improve the new function description a bit. > - Corrected malformed SPDX-License-Identifier in patch20. > > Changes in v7: > - Addressed comments concerning the PSCI changes from Mark Rutland, which moves > the psci firmware driver to a new firmware subdir and change to force PSCI PC > mode during boot to cope with kexec'ed booted kernels. > - Added some maintainers in cc for the timer/nohz patches. > - Minor update to the new genpd governor, taking into account the state's > poweroff latency while validating the sleep duration time. > - Addressed a problem pointed out by Geert Uytterhoeven, around calling > pm_runtime_get|put() for CPUs that has not been attached to a CPU PM domain. > - Re-based on Linus' latest master. > > > Lina Iyer (5): > timer: Export next wakeup time of a CPU > dt: psci: Update DT bindings to support hierarchical PSCI states > cpuidle: dt: Support hierarchical CPU idle states > drivers: firmware: psci: Support hierarchical CPU idle states > arm64: dts: Convert to the hierarchical CPU topology layout for > MSM8916 > > Ulf Hansson (22): > PM / Domains: Add generic data pointer to genpd_power_state struct > PM / Domains: Add support for CPU devices to genpd > PM / Domains: Add genpd governor for CPUs > of: base: Add of_get_cpu_state_node() to get idle states for a CPU > node > ARM/ARM64: cpuidle: Let back-end init ops take the driver as input > drivers: firmware: psci: Move psci to separate directory > MAINTAINERS: Update files for PSCI > drivers: firmware: psci: Split psci_dt_cpu_init_idle() > drivers: firmware: psci: Simplify state node parsing > drivers: firmware: psci: Simplify error path of psci_dt_init() > drivers: firmware: psci: Announce support for OS initiated suspend > mode > drivers: firmware: psci: Prepare to use OS initiated suspend mode > drivers: firmware: psci: Prepare to support PM domains > drivers: firmware: psci: Add support for PM domains using genpd > drivers: firmware: psci: Add hierarchical domain idle states converter > drivers: firmware: psci: Introduce psci_dt_topology_init() > drivers: firmware: psci: Add a helper to attach a CPU to its PM domain > drivers: firmware: psci: Attach the CPU's device to its PM domain > drivers: firmware: psci: Manage runtime PM in the idle path for CPUs > drivers: firmware: psci: Support CPU hotplug for the hierarchical > model > arm64: kernel: Respect the hierarchical CPU topology in DT for PSCI > arm64: dts: hikey: Convert to the hierarchical CPU topology layout > > .../devicetree/bindings/arm/psci.txt | 166 ++++++++ > MAINTAINERS | 2 +- > arch/arm/include/asm/cpuidle.h | 4 +- > arch/arm/kernel/cpuidle.c | 5 +- > arch/arm64/boot/dts/hisilicon/hi6220.dtsi | 87 +++- > arch/arm64/boot/dts/qcom/msm8916.dtsi | 57 ++- > arch/arm64/include/asm/cpu_ops.h | 4 +- > arch/arm64/include/asm/cpuidle.h | 6 +- > arch/arm64/kernel/cpuidle.c | 6 +- > arch/arm64/kernel/setup.c | 3 + > drivers/base/power/domain.c | 74 +++- > drivers/base/power/domain_governor.c | 61 ++- > drivers/cpuidle/cpuidle-arm.c | 2 +- > drivers/cpuidle/dt_idle_states.c | 5 +- > drivers/firmware/Kconfig | 15 +- > drivers/firmware/Makefile | 3 +- > drivers/firmware/psci/Kconfig | 13 + > drivers/firmware/psci/Makefile | 4 + > drivers/firmware/{ => psci}/psci.c | 240 ++++++++--- > drivers/firmware/psci/psci.h | 23 ++ > drivers/firmware/{ => psci}/psci_checker.c | 0 > drivers/firmware/psci/psci_pm_domain.c | 389 ++++++++++++++++++ > drivers/of/base.c | 35 ++ > drivers/soc/qcom/spm.c | 3 +- > include/linux/of.h | 8 + > include/linux/pm_domain.h | 19 +- > include/linux/psci.h | 6 +- > include/linux/tick.h | 8 + > include/uapi/linux/psci.h | 5 + > kernel/time/tick-sched.c | 13 + > 30 files changed, 1163 insertions(+), 103 deletions(-) > create mode 100644 drivers/firmware/psci/Kconfig > create mode 100644 drivers/firmware/psci/Makefile > rename drivers/firmware/{ => psci}/psci.c (76%) > create mode 100644 drivers/firmware/psci/psci.h > rename drivers/firmware/{ => psci}/psci_checker.c (100%) > create mode 100644 drivers/firmware/psci/psci_pm_domain.c > > -- > 2.17.1 >
