From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Tue, 1 Oct 2013 18:15:15 +0100 Subject: [PATCH v3 0/3] MCPM/TC2 support for CPU powerdown synchronisation Message-ID: <1380647718-9178-1-git-send-email-Dave.Martin@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org This series adds MCPM support for detecting when a CPU is safely powered down, and provides an implementation for TC2. It should be possible to implement the same thing for PSCI using the AFFINITY_INFO call (I need to check the semantics with Charles) This is sufficient to for working kexec with real power management on TC2. To test it, you'll also need: * CONFIG_KEXEC=y * CONFIG_PROC_DEVICE_TREE=y * CONFIG_MCPM=y * CONFIG_ARCH_VEXPRESS_TC2_PM=y * sufficiently new kexec-tools (git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git v2.0.4 worked for me) This build on Nico's patch http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=7842/1 (MCPM: don't explode if invoked without being initialized first) To prevent CPUs from running off into the weeds across kexec, this series requires Lorenzo's patch http://lists.infradead.org/pipermail/linux-arm-kernel/2013-September/200917.html (arm: vexpress: tc2: fix hotplug/idle/kexec race on cluster power down). Changes since v2: * Return a proper failure code if mcpm_cpu_power_down_finish() is called with no mcpm platforms_ops registered, or a NULL power_down_finish() method. (Thanks again Nico) * Minor refactoring of the loop in tc2_pm_power_down_finish() to avoid the goto. Changes between v1 and v2: * "Fix" erroneous documentation comment by switching to -errno return value convention for power_down_finish(), which is more informative. tc2_pm now returns -ETIMEDOUT on timeout. The return is adapted to bool convention on return from smp_ops.cpu_kill() instead. (Thanks, Nico). * For consistency, BUG_ON out of range cpu or cluster values tc2_pm_power_down_finish(), as for tc2_pm_power_down(). Changes between RFC and v1: * Print a big fat warning instead of branching to null if the power_down_finish() method is not supplied by the backend, or not registered. * Add a generous timeout of 1 second for the TC2 implementation. * Relax the polling interval to 10ms for TC2, since the need to poll more than once is rare and this is not a performance-critical path. * Fix some silly typos. Dave Martin (3): ARM: mcpm: Factor out logical-to-physical CPU translation ARM: mcpm: Implement cpu_kill() to synchronise on powerdown ARM: vexpress/TC2: Implement MCPM power_down_finish() arch/arm/common/mcpm_entry.c | 15 +++++++++ arch/arm/common/mcpm_platsmp.c | 27 +++++++++++++--- arch/arm/include/asm/mcpm.h | 31 ++++++++++++++++++ arch/arm/mach-vexpress/spc.c | 39 +++++++++++++++++++++++ arch/arm/mach-vexpress/spc.h | 1 + arch/arm/mach-vexpress/tc2_pm.c | 66 ++++++++++++++++++++++++++++++++++++--- 6 files changed, 170 insertions(+), 9 deletions(-) -- 1.7.9.5