| Message ID | 20190722153745.32446-1-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | ARM: psci: cpuidle: PSCI CPUidle rework | expand |
On Mon, 22 Jul 2019 at 17:37, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote: > > Current PSCI CPUidle driver is built on top of the generic ARM > CPUidle infrastructure that relies on the architectural back-end > idle operations to initialize and enter idle states. > > On ARM64 systems, PSCI is the only interface the kernel ever uses > to enter idle states, so, having to rely on a generic ARM CPUidle > driver when there is and there will always be only one method > for entering idle states proved to be overkill, more so given > that on ARM 32-bit systems (that can also enable the generic > ARM CPUidle driver) only one additional idle back-end was > ever added: > > drivers/soc/qcom/spm.c > > and it can be easily converted to a full-fledged CPUidle driver > without requiring the generic ARM CPUidle framework. > > Furthermore, the generic ARM CPUidle infrastructure forces the > PSCI firmware layer to keep CPUidle specific information in it, > which does not really fit its purpose that should be kernel > control/data structure agnostic. > > Lastly, the interface between the generic ARM CPUidle driver and > the arch back-end requires an idle state index to be passed to > suspend operations, with idle states back-end internals (such > as idle state parameters) hidden in architectural back-ends and > not available to the generic ARM CPUidle driver. > > To improve the above mentioned shortcomings, implement a stand > alone PSCI CPUidle driver; this improves the current kernel > code from several perspective: > > - Move CPUidle internal knowledge into CPUidle driver out of > the PSCI firmware interface > - Give the PSCI CPUidle driver control over power state parameters, > in particular in preparation for PSCI OSI support > - Remove generic CPUidle operations infrastructure from the kernel > > This patchset does not go as far as removing the generic ARM CPUidle > infrastructure in order to collect feedback on the new approach > before completing the removal from the kernel, the generic and PSCI > CPUidle driver are left to co-exist. I like the approach and I think this series definitely moves things in the right direction. Of course, some additional cleanups/re-works on top are needed to show its full benefit, but step by step we reach that point. > > Tested on Juno platform with both DT and ACPI boot firmwares. > > Cc: Will Deacon <will@kernel.org> > Cc: Ulf Hansson <ulf.hansson@linaro.org> > Cc: Sudeep Holla <sudeep.holla@arm.com> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> > > Lorenzo Pieralisi (6): > ARM: cpuidle: Remove useless header include > ARM: cpuidle: Remove overzealous error logging > drivers: firmware: psci: Decouple checker from generic ARM CPUidle > ARM: psci: cpuidle: Introduce PSCI CPUidle driver > ARM: psci: cpuidle: Enable PSCI CPUidle driver > PSCI: cpuidle: Refactor CPU suspend power_state parameter handling > > MAINTAINERS | 8 + > arch/arm/configs/imx_v6_v7_defconfig | 1 + > arch/arm64/configs/defconfig | 1 + > arch/arm64/kernel/cpuidle.c | 50 +++++- > arch/arm64/kernel/psci.c | 4 - > drivers/cpuidle/Kconfig.arm | 7 + > drivers/cpuidle/Makefile | 1 + > drivers/cpuidle/cpuidle-arm.c | 13 +- > drivers/cpuidle/cpuidle-psci.c | 235 +++++++++++++++++++++++++++ > drivers/firmware/psci/psci.c | 167 +------------------ > drivers/firmware/psci/psci_checker.c | 16 +- > include/linux/cpuidle.h | 17 +- > include/linux/psci.h | 4 +- > 13 files changed, 338 insertions(+), 186 deletions(-) > create mode 100644 drivers/cpuidle/cpuidle-psci.c > > -- > 2.21.0 > For the series, besides the minor comments I had on patch 4, feel free to add: Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Kind regards Uffe
On Tue, Jul 23, 2019 at 01:49:15PM +0200, Ulf Hansson wrote: > On Mon, 22 Jul 2019 at 17:37, Lorenzo Pieralisi > <lorenzo.pieralisi@arm.com> wrote: > > > > Current PSCI CPUidle driver is built on top of the generic ARM > > CPUidle infrastructure that relies on the architectural back-end > > idle operations to initialize and enter idle states. > > > > On ARM64 systems, PSCI is the only interface the kernel ever uses > > to enter idle states, so, having to rely on a generic ARM CPUidle > > driver when there is and there will always be only one method > > for entering idle states proved to be overkill, more so given > > that on ARM 32-bit systems (that can also enable the generic > > ARM CPUidle driver) only one additional idle back-end was > > ever added: > > > > drivers/soc/qcom/spm.c > > > > and it can be easily converted to a full-fledged CPUidle driver > > without requiring the generic ARM CPUidle framework. > > > > Furthermore, the generic ARM CPUidle infrastructure forces the > > PSCI firmware layer to keep CPUidle specific information in it, > > which does not really fit its purpose that should be kernel > > control/data structure agnostic. > > > > Lastly, the interface between the generic ARM CPUidle driver and > > the arch back-end requires an idle state index to be passed to > > suspend operations, with idle states back-end internals (such > > as idle state parameters) hidden in architectural back-ends and > > not available to the generic ARM CPUidle driver. > > > > To improve the above mentioned shortcomings, implement a stand > > alone PSCI CPUidle driver; this improves the current kernel > > code from several perspective: > > > > - Move CPUidle internal knowledge into CPUidle driver out of > > the PSCI firmware interface > > - Give the PSCI CPUidle driver control over power state parameters, > > in particular in preparation for PSCI OSI support > > - Remove generic CPUidle operations infrastructure from the kernel > > > > This patchset does not go as far as removing the generic ARM CPUidle > > infrastructure in order to collect feedback on the new approach > > before completing the removal from the kernel, the generic and PSCI > > CPUidle driver are left to co-exist. > > I like the approach and I think this series definitely moves things in > the right direction. > > Of course, some additional cleanups/re-works on top are needed to show > its full benefit, but step by step we reach that point. I pushed code out as we agreed. git://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/linux.git branch: cpuidle/psci-driver I will version the code as I update the patches, I will leave them on the list for this week before sending a v2. > > Tested on Juno platform with both DT and ACPI boot firmwares. > > > > Cc: Will Deacon <will@kernel.org> > > Cc: Ulf Hansson <ulf.hansson@linaro.org> > > Cc: Sudeep Holla <sudeep.holla@arm.com> > > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > > Cc: Catalin Marinas <catalin.marinas@arm.com> > > Cc: Mark Rutland <mark.rutland@arm.com> > > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> > > > > Lorenzo Pieralisi (6): > > ARM: cpuidle: Remove useless header include > > ARM: cpuidle: Remove overzealous error logging > > drivers: firmware: psci: Decouple checker from generic ARM CPUidle > > ARM: psci: cpuidle: Introduce PSCI CPUidle driver > > ARM: psci: cpuidle: Enable PSCI CPUidle driver > > PSCI: cpuidle: Refactor CPU suspend power_state parameter handling > > > > MAINTAINERS | 8 + > > arch/arm/configs/imx_v6_v7_defconfig | 1 + > > arch/arm64/configs/defconfig | 1 + > > arch/arm64/kernel/cpuidle.c | 50 +++++- > > arch/arm64/kernel/psci.c | 4 - > > drivers/cpuidle/Kconfig.arm | 7 + > > drivers/cpuidle/Makefile | 1 + > > drivers/cpuidle/cpuidle-arm.c | 13 +- > > drivers/cpuidle/cpuidle-psci.c | 235 +++++++++++++++++++++++++++ > > drivers/firmware/psci/psci.c | 167 +------------------ > > drivers/firmware/psci/psci_checker.c | 16 +- > > include/linux/cpuidle.h | 17 +- > > include/linux/psci.h | 4 +- > > 13 files changed, 338 insertions(+), 186 deletions(-) > > create mode 100644 drivers/cpuidle/cpuidle-psci.c > > > > -- > > 2.21.0 > > > > For the series, besides the minor comments I had on patch 4, feel free to add: > > Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Thanks ! Lorenzo