29 Jan, 2014
6 commits
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Following patch ports the cpuidle framework for powernv
platform and also implements a cpuidle back-end powernv
idle driver calling on to power7_nap and snooze idle states.Signed-off-by: Deepthi Dharwar
Signed-off-by: Benjamin Herrenschmidt -
smt-snooze-delay was designed to disable NAP state or delay the entry
to the NAP state prior to adoption of cpuidle framework. This
is per-cpu variable. With the coming of CPUIDLE framework,
states can be disabled on per-cpu basis using the cpuidle/enable
sysfs entry.Also, with the coming of cpuidle driver each state's target residency
is per-driver unlike earlier which was per-device. Therefore,
the per-cpu sysfs smt-snooze-delay which decides the target residency
of the idle state on a particular cpu causes more confusion to the user
as we cannot have different smt-snooze-delay (target residency)
values for each cpu.In the current code, smt-snooze-delay functionality is completely broken.
It makes sense to remove smt-snooze-delay from idle driver with the
coming of cpuidle framework.
However, sysfs files are retained as ppc64_util currently
utilises it. Once we fix ppc64_util, propose to clean
up the kernel code.Signed-off-by: Deepthi Dharwar
Signed-off-by: Benjamin Herrenschmidt -
This patch removes the usage of MAX_IDLE_STATE macro
and dead code around it. The number of states
are determined at run time based on the cpuidle
state table selected on a given platformSigned-off-by: Deepthi Dharwar
Signed-off-by: Benjamin Herrenschmidt -
Currently cpuidle-pseries backend driver cannot be
built as a module due to dependencies wrt cpuidle framework.
This patch removes all the module related code in the driver.Signed-off-by: Deepthi Dharwar
Signed-off-by: Benjamin Herrenschmidt -
This patch replaces the cpuidle driver and devices initialisation
calls with a single generic cpuidle_register() call
and also includes minor refactoring of the code around it.Remove the cpu online check in snooze loop, as this code can
only locally run on a cpu only if it is online. Therefore,
this check is not required.Signed-off-by: Deepthi Dharwar
Signed-off-by: Benjamin Herrenschmidt -
Move the file from arch specific pseries/processor_idle.c
to drivers/cpuidle/cpuidle-pseries.c
Make the relevant Makefile and Kconfig changes.
Also, introduce Kconfig.powerpc in drivers/cpuidle
for all powerpc cpuidle drivers.Signed-off-by: Deepthi Dharwar
Signed-off-by: Benjamin Herrenschmidt
30 Dec, 2013
1 commit
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Commit 60a66e370007e8535b7a561353b07b37deaf35ba changed the Calxeda
cpuidle driver to a platform driver, copying the __init tag from the
_init() to the newly used _probe() function. However, "probe should
not be __init." (Rob said ;-)
Remove the __init tag to fix a section mismatch in the Calxeda
cpuidle driver.Signed-off-by: Andre Przywara
Signed-off-by: Daniel Lezcano
04 Dec, 2013
1 commit
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If not, we could end up in the unfortunate situation where
we dereference a NULL pointer b/c we have cpuidle disabled.This is the case when booting under Xen (which uses the
ACPI P/C states but disables the CPU idle driver) - and can
be easily reproduced when booting with cpuidle.off=1.BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [] cpuidle_unregister_device+0x2a/0x90
.. snip..
Call Trace:
[] acpi_processor_power_exit+0x3c/0x5c
[] acpi_processor_stop+0x61/0xb6
[] __device_release_driver+0fffff81421653>] device_release_driver+0x23/0x30
[] bus_remove_device+0x108/0x180
[] device_del+0x129/0x1c0
[] ? unregister_xenbus_watch+0x1f0/0x1f0
[] device_unregister+0x1e/0x60
[] unregister_cpu+0x39/0x60
[] arch_unregister_cpu+0x23/0x30
[] handle_vcpu_hotplug_event+0xc1/0xe0
[] xenwatch_thread+0x45/0x120
[] ? abort_exclusive_wait+0xb0/0xb0
[] kthread+0xd2/0xf0
[] ? kthread_create_on_node+0x180/0x180
[] ret_from_fork+0x7c/0xb0
[] ? kthread_create_on_node+0x180/0x180This problem also appears in 3.12 and could be a candidate for backport.
Signed-off-by: Konrad Rzeszutek Wilk
Cc: All applicable
Signed-off-by: Rafael J. Wysocki
14 Nov, 2013
1 commit
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Pull ACPI and power management updates from Rafael J Wysocki:
- New power capping framework and the the Intel Running Average Power
Limit (RAPL) driver using it from Srinivas Pandruvada and Jacob Pan.- Addition of the in-kernel switching feature to the arm_big_little
cpufreq driver from Viresh Kumar and Nicolas Pitre.- cpufreq support for iMac G5 from Aaro Koskinen.
- Baytrail processors support for intel_pstate from Dirk Brandewie.
- cpufreq support for Midway/ECX-2000 from Mark Langsdorf.
- ARM vexpress/TC2 cpufreq support from Sudeep KarkadaNagesha.
- ACPI power management support for the I2C and SPI bus types from Mika
Westerberg and Lv Zheng.- cpufreq core fixes and cleanups from Viresh Kumar, Srivatsa S Bhat,
Stratos Karafotis, Xiaoguang Chen, Lan Tianyu.- cpufreq drivers updates (mostly fixes and cleanups) from Viresh
Kumar, Aaro Koskinen, Jungseok Lee, Sudeep KarkadaNagesha, Lukasz
Majewski, Manish Badarkhe, Hans-Christian Egtvedt, Evgeny Kapaev.- intel_pstate updates from Dirk Brandewie and Adrian Huang.
- ACPICA update to version 20130927 includig fixes and cleanups and
some reduction of divergences between the ACPICA code in the kernel
and ACPICA upstream in order to improve the automatic ACPICA patch
generation process. From Bob Moore, Lv Zheng, Tomasz Nowicki, Naresh
Bhat, Bjorn Helgaas, David E Box.- ACPI IPMI driver fixes and cleanups from Lv Zheng.
- ACPI hotplug fixes and cleanups from Bjorn Helgaas, Toshi Kani, Zhang
Yanfei, Rafael J Wysocki.- Conversion of the ACPI AC driver to the platform bus type and
multiple driver fixes and cleanups related to ACPI from Zhang Rui.- ACPI processor driver fixes and cleanups from Hanjun Guo, Jiang Liu,
Bartlomiej Zolnierkiewicz, Mathieu Rhéaume, Rafael J Wysocki.- Fixes and cleanups and new blacklist entries related to the ACPI
video support from Aaron Lu, Felipe Contreras, Lennart Poettering,
Kirill Tkhai.- cpuidle core cleanups from Viresh Kumar and Lorenzo Pieralisi.
- cpuidle drivers fixes and cleanups from Daniel Lezcano, Jingoo Han,
Bartlomiej Zolnierkiewicz, Prarit Bhargava.- devfreq updates from Sachin Kamat, Dan Carpenter, Manish Badarkhe.
- Operation Performance Points (OPP) core updates from Nishanth Menon.
- Runtime power management core fix from Rafael J Wysocki and update
from Ulf Hansson.- Hibernation fixes from Aaron Lu and Rafael J Wysocki.
- Device suspend/resume lockup detection mechanism from Benoit Goby.
- Removal of unused proc directories created for various ACPI drivers
from Lan Tianyu.- ACPI LPSS driver fix and new device IDs for the ACPI platform scan
handler from Heikki Krogerus and Jarkko Nikula.- New ACPI _OSI blacklist entry for Toshiba NB100 from Levente Kurusa.
- Assorted fixes and cleanups related to ACPI from Andy Shevchenko, Al
Stone, Bartlomiej Zolnierkiewicz, Colin Ian King, Dan Carpenter,
Felipe Contreras, Jianguo Wu, Lan Tianyu, Yinghai Lu, Mathias Krause,
Liu Chuansheng.- Assorted PM fixes and cleanups from Andy Shevchenko, Thierry Reding,
Jean-Christophe Plagniol-Villard.* tag 'pm+acpi-3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (386 commits)
cpufreq: conservative: fix requested_freq reduction issue
ACPI / hotplug: Consolidate deferred execution of ACPI hotplug routines
PM / runtime: Use pm_runtime_put_sync() in __device_release_driver()
ACPI / event: remove unneeded NULL pointer check
Revert "ACPI / video: Ignore BIOS initial backlight value for HP 250 G1"
ACPI / video: Quirk initial backlight level 0
ACPI / video: Fix initial level validity test
intel_pstate: skip the driver if ACPI has power mgmt option
PM / hibernate: Avoid overflow in hibernate_preallocate_memory()
ACPI / hotplug: Do not execute "insert in progress" _OST
ACPI / hotplug: Carry out PCI root eject directly
ACPI / hotplug: Merge device hot-removal routines
ACPI / hotplug: Make acpi_bus_hot_remove_device() internal
ACPI / hotplug: Simplify device ejection routines
ACPI / hotplug: Fix handle_root_bridge_removal()
ACPI / hotplug: Refuse to hot-remove all objects with disabled hotplug
ACPI / scan: Start matching drivers after trying scan handlers
ACPI: Remove acpi_pci_slot_init() headers from internal.h
ACPI / blacklist: fix name of ThinkPad Edge E530
PowerCap: Fix build error with option -Werror=format-security
...Conflicts:
arch/arm/mach-omap2/opp.c
drivers/Kconfig
drivers/spi/spi.c
30 Oct, 2013
12 commits
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cpuidle_unregister_governor() and cpuidle_replace_governor() aren't
used anymore and can be removed. They were used by cpufreq governors
earlier, but since the governors can't be compiled as modules any
more, these two functions aren't necessary.Suggested-by: Daniel Lezcano
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
poll_idle_init() just initializes drv->states[0] and so that is
required to be done only once for each driver. Currently, it is
called from cpuidle_enable_device() which is called for every CPU
that the driver supports. That is not required, so move it to a
better place and call it from __cpuidle_register_driver() so that
the initialization is carried out only once.Acked-by: Daniel Lezcano
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
Instances of "struct cpuidle_driver *" are consistently named as "drv"
in the cpuidle core except in show_current_driver().Make that function use variable naming consistent with the rest of the
code.[rjw: Changelog]
Acked-by: Daniel Lezcano
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
There are a few cpuidle_get_driver() calls that aren't made under
cpuidle_driver_lock which is incorrect.Fix them by calling cpuidle_get_driver() after taking cpuidle_driver_lock.
Acked-by: Daniel Lezcano
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
Few statements in cpuidle_idle_call() are broken into multiple lines,
although that isn't really necessary. Convert those to single line.Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
We are doing this twice in cpuidle_idle_call() routine:
drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOPWould be better if we actually store this in a local variable and
use that. That reduces code duplication and likely makes this piece
of code run faster (in case the compiler wasn't able to optimize it
earlier)[rjw: Cast the result of bitwise AND to bool explicitly using !!]
Acked-by: Daniel Lezcano
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
Two checks cpuidle_idle_call() cause the same error code to be
returned if they fail, so merge them for clarity.[rjw: Changelog]
Acked-by: Daniel Lezcano
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
This patch rearranges __cpuidle_register_device() a bit in order to
reduce the number of exit points in that function.Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
This is trivial patch that just reorders a few statements in
__cpuidle_driver_init() routine so that we don't need both 'continue'
and 'break' in the for loop. Functionally it shouldn't change anything.Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
The only value returned by __cpuidle_driver_init() is 0, so it
very well may be a void function.[rjw: Changelog]
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
The only value returned by __cpuidle_device_init() is 0, so it very
well may be a void function. Make that happen.[rjw: Changelog]
Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki -
Some comments in cpuidle core files contain trivial mistakes.
This patch fixes them.Signed-off-by: Viresh Kumar
Signed-off-by: Rafael J. Wysocki
17 Oct, 2013
1 commit
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As the cpuidle driver code has no more the dependency with the pm code, the
'standby' callback being passed as a parameter to the device's platform data,
we can move the cpuidle driver in the drivers/cpuidle directory.Signed-off-by: Daniel Lezcano
Acked-by: Jean-Christophe PLAGNIOL-VILLARD
Acked-by: Nicolas FerreConflicts:
drivers/cpuidle/Kconfig.arm
drivers/cpuidle/Makefile
07 Oct, 2013
4 commits
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The dbx500_cpuidle_probe is tagged as an __init section but the variable
dbx500_cpuidle_plat_driver is not.The dbx500_cpuidle_probe could not be declared as __init because of macro
module_platform_driver builds the exit function, tags as __exit and this one
refers to the dbx500_cpuidle_plat_driver which is an __initdata.That leads to a section mismatch.
Fix it by removing the __init tag for the probe function.
Signed-off-by: Daniel Lezcano
Acked-by: Linus Walleij -
As the ux500 and the kirkwood driver, make the zynq driver a platform driver
Signed-off-by: Daniel Lezcano
Acked-by: Michal Simek
Tested-by: Soren Brinkmann -
All zynq platforms have this compatibility string and there is no any other
clone.Signed-off-by: Daniel Lezcano
Acked-by: Michal Simek -
Following the reorganization of CPU idle drivers configurations into an ARM
specific Kconfig, the existing idle drivers Kconfig entries were renamed and
moved to the Kconfig.arm file. Makefile entries were updated accordingly.This patch renames the entries in Kconfig.arm and makefile to make the newly
added big.LITTLE CPUidle driver compliant with the new naming convention.Signed-off-by: Lorenzo Pieralisi
Acked-by: Kevin Hilman
Signed-off-by: Daniel Lezcano
02 Oct, 2013
3 commits
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This updates the Calxeda cpuidle driver to use PSCI calls to powergate
cores. This also enables cpuidle for the ECX-2000.This could possibly become a generic PSCI driver, but there are no other
PSCI users in the kernel other than mach-virt.Signed-off-by: Rob Herring
Cc: "Rafael J. Wysocki"
Acked-by: Daniel Lezcano
Cc: linux-pm@vger.kernel.org -
As the ux500 and the kirkwood driver, make the calxeda driver a platform driver
[Compiled only]
Signed-off-by: Daniel Lezcano
Signed-off-by: Rob Herring -
Wnen powergating the core, we need to call cpu pm notifiers to save VFP
state (!SMP only) and resetting the breakpoint h/w.Signed-off-by: Rob Herring
Cc: "Rafael J. Wysocki"
Acked-by: Daniel Lezcano
Cc: linux-pm@vger.kernel.org
13 Sep, 2013
1 commit
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Pull ACPI and power management fixes from Rafael Wysocki:
"All of these commits are fixes that have emerged recently and some of
them fix bugs introduced during this merge window.Specifics:
1) ACPI-based PCI hotplug (ACPIPHP) fixes related to spurious events
After the recent ACPIPHP changes we've seen some interesting
breakage on a system that triggers device check notifications
during boot for non-existing devices. Although those
notifications are really spurious, we should be able to deal with
them nevertheless and that shouldn't introduce too much overhead.
Four commits to make that work properly.2) Memory hotplug and hibernation mutual exclusion rework
This was maent to be a cleanup, but it happens to fix a classical
ABBA deadlock between system suspend/hibernation and ACPI memory
hotplug which is possible if they are started roughly at the same
time. Three commits rework memory hotplug so that it doesn't
acquire pm_mutex and make hibernation use device_hotplug_lock
which prevents it from racing with memory hotplug.3) ACPI Intel LPSS (Low-Power Subsystem) driver crash fix
The ACPI LPSS driver crashes during boot on Apple Macbook Air with
Haswell that has slightly unusual BIOS configuration in which one
of the LPSS device's _CRS method doesn't return all of the
information expected by the driver. Fix from Mika Westerberg, for
stable.4) ACPICA fix related to Store->ArgX operation
AML interpreter fix for obscure breakage that causes AML to be
executed incorrectly on some machines (observed in practice).
From Bob Moore.5) ACPI core fix for PCI ACPI device objects lookup
There still are cases in which there is more than one ACPI device
object matching a given PCI device and we don't choose the one
that the BIOS expects us to choose, so this makes the lookup take
more criteria into account in those cases.6) Fix to prevent cpuidle from crashing in some rare cases
If the result of cpuidle_get_driver() is NULL, which can happen on
some systems, cpuidle_driver_ref() will crash trying to use that
pointer and the Daniel Fu's fix prevents that from happening.7) cpufreq fixes related to CPU hotplug
Stephen Boyd reported a number of concurrency problems with
cpufreq related to CPU hotplug which are addressed by a series of
fixes from Srivatsa S Bhat and Viresh Kumar.8) cpufreq fix for time conversion in time_in_state attribute
Time conversion carried out by cpufreq when user space attempts to
read /sys/devices/system/cpu/cpu*/cpufreq/stats/time_in_state
won't work correcty if cputime_t doesn't map directly to jiffies.
Fix from Andreas Schwab.9) Revert of a troublesome cpufreq commit
Commit 7c30ed5 (cpufreq: make sure frequency transitions are
serialized) was intended to address some known concurrency
problems in cpufreq related to the ordering of transitions, but
unfortunately it introduced several problems of its own, so I
decided to revert it now and address the original problems later
in a more robust way.10) Intel Haswell CPU models for intel_pstate from Nell Hardcastle.
11) cpufreq fixes related to system suspend/resume
The recent cpufreq changes that made it preserve CPU sysfs
attributes over suspend/resume cycles introduced a possible NULL
pointer dereference that caused it to crash during the second
attempt to suspend. Three commits from Srivatsa S Bhat fix that
problem and a couple of related issues.12) cpufreq locking fix
cpufreq_policy_restore() should acquire the lock for reading, but
it acquires it for writing. Fix from Lan Tianyu"* tag 'pm+acpi-fixes-3.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (25 commits)
cpufreq: Acquire the lock in cpufreq_policy_restore() for reading
cpufreq: Prevent problems in update_policy_cpu() if last_cpu == new_cpu
cpufreq: Restructure if/else block to avoid unintended behavior
cpufreq: Fix crash in cpufreq-stats during suspend/resume
intel_pstate: Add Haswell CPU models
Revert "cpufreq: make sure frequency transitions are serialized"
cpufreq: Use signed type for 'ret' variable, to store negative error values
cpufreq: Remove temporary fix for race between CPU hotplug and sysfs-writes
cpufreq: Synchronize the cpufreq store_*() routines with CPU hotplug
cpufreq: Invoke __cpufreq_remove_dev_finish() after releasing cpu_hotplug.lock
cpufreq: Split __cpufreq_remove_dev() into two parts
cpufreq: Fix wrong time unit conversion
cpufreq: serialize calls to __cpufreq_governor()
cpufreq: don't allow governor limits to be changed when it is disabled
ACPI / bind: Prefer device objects with _STA to those without it
ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device checks
ACPI / hotplug / PCI: Use _OST to notify firmware about notify status
ACPI / hotplug / PCI: Avoid doing too much for spurious notifies
ACPICA: Fix for a Store->ArgX when ArgX contains a reference to a field.
ACPI / hotplug / PCI: Don't trim devices before scanning the namespace
...
10 Sep, 2013
1 commit
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Pull ARM SoC driver update from Kevin Hilman:
"This contains the ARM SoC related driver updates for v3.12. The only
thing this cycle are core PM updates and CPUidle support for ARM's TC2
big.LITTLE development platform"* tag 'drivers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
cpuidle: big.LITTLE: vexpress-TC2 CPU idle driver
ARM: vexpress: tc2: disable GIC CPU IF in tc2_pm_suspend
drivers: irq-chip: irq-gic: introduce gic_cpu_if_down()
31 Aug, 2013
1 commit
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If the current CPU has no cpuidle driver, drv will be NULL in
cpuidle_driver_ref(). Check if that is the case before trying
to bump up the driver's refcount to prevent the kernel from
crashing.[rjw: Subject and changelog]
Signed-off-by: Daniel Fu
Signed-off-by: Rafael J. Wysocki
30 Aug, 2013
3 commits
-
The coupled cpuidle waiting loop clears pending pokes before
entering the safe state. If a poke arrives just before the
pokes are cleared, but after the while loop condition checks,
the poke will be lost and the cpu will stay in the safe state
until another interrupt arrives. This may cause the cpu that
sent the poke to spin in the ready loop with interrupts off
until another cpu receives an interrupt, and if no other cpus
have interrupts routed to them it can spin forever.Change the return value of cpuidle_coupled_clear_pokes to
return if a poke was cleared, and move the need_resched()
checks into the callers. In the waiting loop, if
a poke was cleared restart the loop to repeat the while
condition checks.Reported-by: Neil Zhang
Signed-off-by: Colin Cross
Cc: 3.6+ # 3.6+
Signed-off-by: Rafael J. Wysocki -
Joseph Lo reported a lockup on Tegra20 caused
by a race condition in coupled cpuidle. When two or more cpus
enter idle at the same time, the first cpus to arrive may go to the
ready loop without processing pending pokes from the last cpu to
arrive.This patch adds a check for pending pokes once all cpus have been
synchronized in the ready loop and resets the coupled state and
retries if any cpus failed to handle their pending poke.Retrying on all cpus may trigger the same issue again, so this patch
also adds a check to ensure that each cpu has received at least one
poke between when it enters the waiting loop and when it moves on to
the ready loop.Reported-and-tested-by: Joseph Lo
Tested-by: Stephen Warren
Signed-off-by: Colin Cross
Cc: 3.6+ # 3.6+
Signed-off-by: Rafael J. Wysocki -
Calling cpuidle_enter_state is expected to return with interrupts
enabled, but interrupts must be disabled before starting the
ready loop synchronization stage. Call local_irq_disable after
each call to cpuidle_enter_state for the safe state.Tested-by: Stephen Warren
Signed-off-by: Colin Cross
Signed-off-by: Rafael J. Wysocki
29 Aug, 2013
2 commits
-
From Lorenzo Pieralisi:
This patch series contains:- GIC driver update to add a method to disable the GIC CPU IF
- TC2 MCPM update to add GIC CPU disabling to suspend method
- TC2 CPU idle big.LITTLE driver* cpuidle/biglittle:
cpuidle: big.LITTLE: vexpress-TC2 CPU idle driver
ARM: vexpress: tc2: disable GIC CPU IF in tc2_pm_suspend
drivers: irq-chip: irq-gic: introduce gic_cpu_if_down()
ARM: vexpress/TC2: implement PM suspend method
ARM: vexpress/TC2: basic PM support
ARM: vexpress: Add SCC to V2P-CA15_A7's device tree
ARM: vexpress/TC2: add Serial Power Controller (SPC) support
ARM: vexpress/dcscb: fix cache disabling sequencesSigned-off-by: Olof Johansson
-
The big.LITTLE architecture is composed of two clusters of cpus. One cluster
contains less powerful but more energy efficient processors and the other
cluster groups the powerful but energy-intensive cpus.The TC2 testchip implements two clusters of CPUs (A7 and A15 clusters in
a big.LITTLE configuration) connected through a CCI interconnect that manages
coherency of their respective L2 caches and intercluster distributed
virtual memory messages (DVM).TC2 testchip integrates a power controller that manages cores resets, wake-up
IRQs and cluster low-power states. Power states are managed at cluster
level, which means that voltage is removed from a cluster iff all cores
in a cluster are in a wfi state. Single cores can enter a reset state
which is identical to wfi in terms of power consumption but simplifies the
way cluster states are entered.This patch provides a multiple driver CPU idle implementation for TC2
which paves the way for a generic big.LITTLE idle driver for all
upcoming big.LITTLE based systems on chip.The driver relies on the MCPM infrastructure to coordinate and manage
core power states; in particular MCPM allows to suspend specific cores
and hides the CPUs coordination required to shut-down clusters of CPUs.Power down sequences for the respective clusters are implemented in the
MCPM TC2 backend, with all code needed to clean caches and exit coherency.The multiple driver CPU idle infrastructure allows to define different
C-states for big and little cores, determined at boot by checking the
part id of the possible CPUs and initializing the respective logical
masks in the big and little drivers.Current big.little systems are composed of A7 and A15 clusters, as
implemented in TC2, but in the future that may change and the driver
will have evolve to retrieve what is a 'big' cpu and what is a 'little'
cpu in order to build the correct topology.Cc: Kevin Hilman
Cc: Amit Kucheria
Cc: Olof Johansson
Cc: Nicolas Pitre
Cc: Rafael J. Wysocki
Signed-off-by: Daniel Lezcano
Signed-off-by: Lorenzo Pieralisi
Signed-off-by: Olof Johansson
23 Aug, 2013
3 commits
-
Field predicted_us value can never exceed expected_us value, but it has
a potentially larger type. As there is no need for additional 32 bits of
zeroes on 32 bit plaforms, change the type of predicted_us to match the
type of expected_us.Field correction_factor is used to store a value that cannot exceed the
product of RESOLUTION and DECAY (default 1024*8 = 8192). The constants
cannot in practice be incremented to such values, that they'd overflow
unsigned int even on 32 bit systems, so the type is changed to avoid
unnecessary 64 bit arithmetic on 32 bit systems.One multiplication of (now) 32 bit values needs an added cast to avoid
truncation of the result and has been added.In order to avoid another multiplication from 32 bit domain to 64 bit
domain, the new correction_factor calculation has been changed from
new = old * (DECAY-1) / DECAY
to
new = old - old / DECAY,
which with infinite precision would yeild exactly the same result, but
now changes the direction of rounding. The impact is not significant as
the maximum accumulated difference cannot exceed the value of DECAY,
which is relatively small compared to product of RESOLUTION and DECAY
(8 / 8192).Signed-off-by: Tuukka Tikkanen
Signed-off-by: Rafael J. Wysocki -
The menu governor has a number of tunable constants that may be changed
in the source. If certain combination of values are chosen, an overflow
is possible when the correction_factor is being recalculated.This patch adds a warning regarding this possibility and describes the
change needed for fixing the issue. The change should not be permanently
enabled, as it will hurt performance when it is not needed.Signed-off-by: Tuukka Tikkanen
Signed-off-by: Rafael J. Wysocki -
The menu governor uses a static function get_typical_interval() to
try to detect a repeating pattern of wakeups. The previous interval
durations are stored as an array of unsigned ints, but the arithmetic
in the function is performed exclusively as 64 bit values, even when
the value stored in a variable is known not to exceed unsigned int,
which may be smaller and more efficient on some platforms.This patch changes the types of varibles used to store some
intermediates, the maximum and and the cutoff threshold to unsigned
ints. Average and standard deviation are still treated as 64 bit values,
even when the values are known to be within the domain of unsigned int,
to avoid casts to ensure correct integer promotion for arithmetic
operations.Signed-off-by: Tuukka Tikkanen
Signed-off-by: Rafael J. Wysocki
