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Some OpenPOWER boxes can have same pstate values for nominal and
pmin pstates. In these boxes the current code will not initialize
'powernv_pstate_info.min' variable and result in erroneous CPU
frequency reporting. This patch fixes this problem.
Fixes: 09ca4c9b5958 (cpufreq: powernv: Replacing pstate_id with frequency table index)
Reported-by: Alvin Wang <wangat@tw.ibm.com>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.8+ <stable@vger.kernel.org> # 4.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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On POWER8 and POWER9, the PMSR and the PMCR registers define pstates
to be 8-bit wide values. The device-tree exports pstates as 32-bit
wide values of which the lower byte is the actual pstate.
The current implementation in the kernel treats pstates as integer
type, since it used to use the sign of the pstate for performing some
boundary-checks. This is no longer required after the patch
"powernv-cpufreq: Fix pstate_to_idx() to handle non-continguous
pstates".
So, in this patch, we modify the powernv-cpufreq driver to uniformly
treat pstates as opaque 8-bit values obtained from the device-tree or
the PMCR. This simplifies the extract_pstate() helper function since
we no longer no longer require to worry about the sign-extentions.
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The code in powernv-cpufreq, makes the following two assumptions which
are not guaranteed by the device-tree bindings:
1) Pstate ids are continguous: This is used in pstate_to_idx() to
obtain the reverse map from a pstate to it's corresponding
entry into the cpufreq frequency table.
2) Every Pstate should always lie between the max and the min
pstates that are explicitly reported in the device tree: This
is used to determine whether a pstate reported by the PMSR is
out of bounds.
Both these assumptions are unwarranted and can change on future
platforms.
In this patch, we maintain the reverse map from a pstate to it's index
in the cpufreq frequency table and use this in pstate_to_idx(). This
does away with the assumptions (1) mentioned above, and will work with
non continguous pstate ids. If no entry exists for a particular
pstate, then such a pstate is treated as being out of bounds. This
gets rid of assumption (2).
On all the existing platforms, where the pstates are 8-bit long
values, the new implementation of pstate_to_idx() takes constant time.
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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On POWERNV platform, the fields for pstates in the Power Management
Status Register (PMSR) and the Power Management Control Register
(PMCR) are 8-bits wide. On POWER8 the pstates are negatively numbered
while on POWER9 they are positively numbered.
The device-tree exports pstates as 32-bit entries. The device-tree
implementation sign-extends the 8-bit pstate values to obtain the
corresponding 32-bit entry.
Eg: On POWER8, a pstate value 0x82 [-126] is represented in the
device-tree as 0xfffffff82 while on POWER9, the same value 0x82 [130]
is represented in the device-tree as 0x00000082.
The powernv-cpufreq driver implementation represents pstates using the
integer type. In multiple places in the driver, the code interprets
the pstates extracted from the PMSR as a signed byte and assigns it to
a integer variable to get the sign-extention.
On POWER9 platforms which have greater than 128 pstates, this results
in the driver performing incorrect sign-extention, and thereby
treating a legitimate pstate (say 130) as an invalid pstates (since it
is interpreted as -126).
This patch fixes the issue by implementing a helper function to
extract Pstates from PMSR register, and correctly sign-extend it to be
consistent with the values provided by the device-tree.
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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This refactors the only user of init_timer_pinned_deferrable() to use the
new timer_setup() and from_timer(). Adds a pointer back to the policy,
and drops the definition of init_timer_pinned_deferrable().
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: Petr Mladek <pmladek@suse.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux1394-devel@lists.sourceforge.net
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-s390@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ursula Braun <ubraun@linux.vnet.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Harish Patil <harish.patil@cavium.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Manish Chopra <manish.chopra@cavium.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-pm@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Gross <mark.gross@intel.com>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Michael Reed <mdr@sgi.com>
Cc: netdev@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lkml.kernel.org/r/1507159627-127660-3-git-send-email-keescook@chromium.org
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In P8+, Workload Optimized Frequency(WOF) provides the capability to
boost the cpu frequency based on the utilization of the other cpus
running in the chip. The On-Chip-Controller(OCC) firmware will control
the achievability of these frequencies depending on the power headroom
available in the chip. Currently the ultra-turbo frequencies provided
by this feature are exported along with the turbo and sub-turbo
frequencies as scaling_available_frequencies. This patch will export
the ultra-turbo frequencies separately as scaling_boost_frequencies in
WOF enabled systems. This patch will add the boost sysfs file which
can be used to disable/enable ultra-turbo frequencies.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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With preemption turned on we can read incorrect throttling state
while being switched to CPU on a different chip.
BUG: using smp_processor_id() in preemptible [00000000] code: cat/7343
caller is .powernv_cpufreq_throttle_check+0x2c/0x710
CPU: 13 PID: 7343 Comm: cat Not tainted 4.8.0-rc5-dirty #1
Call Trace:
[c0000007d25b75b0] [c000000000971378] .dump_stack+0xe4/0x150 (unreliable)
[c0000007d25b7640] [c0000000005162e4] .check_preemption_disabled+0x134/0x150
[c0000007d25b76e0] [c0000000007b63ac] .powernv_cpufreq_throttle_check+0x2c/0x710
[c0000007d25b7790] [c0000000007b6d18] .powernv_cpufreq_target_index+0x288/0x360
[c0000007d25b7870] [c0000000007acee4] .__cpufreq_driver_target+0x394/0x8c0
[c0000007d25b7920] [c0000000007b22ac] .cpufreq_set+0x7c/0xd0
[c0000007d25b79b0] [c0000000007adf50] .store_scaling_setspeed+0x80/0xc0
[c0000007d25b7a40] [c0000000007ae270] .store+0xa0/0x100
[c0000007d25b7ae0] [c0000000003566e8] .sysfs_kf_write+0x88/0xb0
[c0000007d25b7b70] [c0000000003553b8] .kernfs_fop_write+0x178/0x260
[c0000007d25b7c10] [c0000000002ac3cc] .__vfs_write+0x3c/0x1c0
[c0000007d25b7cf0] [c0000000002ad584] .vfs_write+0xc4/0x230
[c0000007d25b7d90] [c0000000002aeef8] .SyS_write+0x58/0x100
[c0000007d25b7e30] [c00000000000bfec] system_call+0x38/0xfc
Fixes: 09a972d16209 (cpufreq: powernv: Report cpu frequency throttling)
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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lpstate_idx remains uninitialized in the case when elapsed_time
is greater than MAX_RAMP_DOWN_TIME. At the end of rampdown the
global pstate should be equal to the local pstate.
Fixes: 20b15b766354 (cpufreq: powernv: Use PMCR to verify global and localpstate)
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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As fast_switch() may get called with interrupt disable mode, we cannot
hold a mutex to update the global_pstate_info. So currently, fast_switch()
does not update the global_pstate_info and it will end up with stale data
whenever pstate is updated through fast_switch().
As the gpstate_timer can fire after fast_switch() has updated the pstates,
the timer handler cannot rely on the cached values of local and global
pstate and needs to read it from the PMCR.
Only gpstate_timer_handler() is affected by the stale cached pstate data
beacause either fast_switch() or target_index() routines will be called
for a given govenor, but gpstate_timer can fire after the governor has
changed to schedutil.
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Adding fast_switch which does light weight operation to set the desired
pstate. Both global and local pstates are set to the same desired pstate.
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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* pm-sleep:
PM / hibernate: Restore processor state before using per-CPU variables
x86/power/64: Always create temporary identity mapping correctly
* pm-cpufreq:
cpufreq: powernv: Fix crash in gpstate_timer_handler()
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Commit 09ca4c9b5958 (cpufreq: powernv: Replacing pstate_id with
frequency table index) changes calc_global_pstate() to use
cpufreq_table index instead of pstate_id.
But in gpstate_timer_handler(), pstate_id was being passed instead
of cpufreq_table index, which caused index_to_pstate() to access
out of bound indices, leading to this crash.
Adding sanity check for index and pstate, to ensure only valid pstate
and index values are returned.
Call Trace:
[c00000078d66b130] [c00000000011d224] __free_irq+0x234/0x360
(unreliable)
[c00000078d66b1c0] [c00000000011d44c] free_irq+0x6c/0xa0
[c00000078d66b1f0] [c00000000006c4f8] opal_event_shutdown+0x88/0xd0
[c00000078d66b230] [c000000000067a4c] opal_shutdown+0x1c/0x90
[c00000078d66b260] [c000000000063a00] pnv_shutdown+0x20/0x40
[c00000078d66b280] [c000000000021538] machine_restart+0x38/0x90
[c0000000078d66b310] [c000000000965ea0] panic+0x284/0x300
[c00000078d66b3a0] [c00000000001f508] die+0x388/0x450
[c00000078d66b430] [c000000000045a50] bad_page_fault+0xd0/0x140
[c00000078d66b4a0] [c000000000008964] handle_page_fault+0x2c/0x30
interrupt: 300 at gpstate_timer_handler+0x150/0x260
LR = gpstate_timer_handler+0x130/0x260
[c00000078d66b7f0] [c000000000132b58] call_timer_fn+0x58/0x1c0
[c00000078d66b880] [c000000000132e20] expire_timers+0x130/0x1d0
[c00000078d66b8f0] [c000000000133068] run_timer_softirq+0x1a8/0x230
[c00000078d66b980] [c0000000000b535c] __do_softirq+0x18c/0x400
[c00000078d66ba70] [c0000000000b5828] irq_exit+0xc8/0x100
[c00000078d66ba90] [c00000000001e214] timer_interrupt+0xa4/0xe0
[c00000078d66bac0] [c0000000000027d0] decrementer_common+0x150/0x180
interrupt: 901 at arch_local_irq_restore+0x74/0x90
0] [c000000000106b34] call_cpuidle+0x44/0x90
[c00000078d66be50] [c00000000010708c] cpu_startup_entry+0x38c/0x460
[c00000078d66bf20] [c00000000003d930] start_secondary+0x330/0x380
[c00000078d66bf90] [c000000000008e6c] start_secondary_prolog+0x10/0x14
Fixes: 09ca4c9b5958 (cpufreq: powernv: Replacing pstate_id with frequency table index)
Reported-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"Again, the majority of changes go into the cpufreq subsystem, but
there are no big features this time. The cpufreq changes that stand
out somewhat are the governor interface rework and improvements
related to the handling of frequency tables. Apart from those, there
are fixes and new device/CPU IDs in drivers, cleanups and an
improvement of the new schedutil governor.
Next, there are some changes in the hibernation core, including a fix
for a nasty problem related to the MONITOR/MWAIT usage by CPU offline
during resume from hibernation, a few core improvements related to
memory management during resume, a couple of additional debug features
and cleanups.
Finally, we have some fixes and cleanups in the devfreq subsystem,
generic power domains framework improvements related to system
suspend/resume, support for some new chips in intel_idle and in the
power capping RAPL driver, a new version of the AnalyzeSuspend utility
and some assorted fixes and cleanups.
Specifics:
- Rework the cpufreq governor interface to make it more
straightforward and modify the conservative governor to avoid using
transition notifications (Rafael Wysocki).
- Rework the handling of frequency tables by the cpufreq core to make
it more efficient (Viresh Kumar).
- Modify the schedutil governor to reduce the number of wakeups it
causes to occur in cases when the CPU frequency doesn't need to be
changed (Steve Muckle, Viresh Kumar).
- Fix some minor issues and clean up code in the cpufreq core and
governors (Rafael Wysocki, Viresh Kumar).
- Add Intel Broxton support to the intel_pstate driver (Srinivas
Pandruvada).
- Fix problems related to the config TDP feature and to the validity
of the MSR_HWP_INTERRUPT register in intel_pstate (Jan Kiszka,
Srinivas Pandruvada).
- Make intel_pstate update the cpu_frequency tracepoint even if the
frequency doesn't change to avoid confusing powertop (Rafael
Wysocki).
- Clean up the usage of __init/__initdata in intel_pstate, mark some
of its internal variables as __read_mostly and drop an unused
structure element from it (Jisheng Zhang, Carsten Emde).
- Clean up the usage of some duplicate MSR symbols in intel_pstate
and turbostat (Srinivas Pandruvada).
- Update/fix the powernv, s3c24xx and mvebu cpufreq drivers (Akshay
Adiga, Viresh Kumar, Ben Dooks).
- Fix a regression (introduced during the 4.5 cycle) in the
pcc-cpufreq driver by reverting the problematic commit (Andreas
Herrmann).
- Add support for Intel Denverton to intel_idle, clean up Broxton
support in it and make it explicitly non-modular (Jacob Pan, Jan
Beulich, Paul Gortmaker).
- Add support for Denverton and Ivy Bridge server to the Intel RAPL
power capping driver and make it more careful about the handing of
MSRs that may not be present (Jacob Pan, Xiaolong Wang).
- Fix resume from hibernation on x86-64 by making the CPU offline
during resume avoid using MONITOR/MWAIT in the "play dead" loop
which may lead to an inadvertent "revival" of a "dead" CPU and a
page fault leading to a kernel crash from it (Rafael Wysocki).
- Make memory management during resume from hibernation more
straightforward (Rafael Wysocki).
- Add debug features that should help to detect problems related to
hibernation and resume from it (Rafael Wysocki, Chen Yu).
- Clean up hibernation core somewhat (Rafael Wysocki).
- Prevent KASAN from instrumenting the hibernation core which leads
to large numbers of false-positives from it (James Morse).
- Prevent PM (hibernate and suspend) notifiers from being called
during the cleanup phase if they have not been called during the
corresponding preparation phase which is possible if one of the
other notifiers returns an error at that time (Lianwei Wang).
- Improve suspend-related debug printout in the tasks freezer and
clean up suspend-related console handling (Roger Lu, Borislav
Petkov).
- Update the AnalyzeSuspend script in the kernel sources to version
4.2 (Todd Brandt).
- Modify the generic power domains framework to make it handle system
suspend/resume better (Ulf Hansson).
- Make the runtime PM framework avoid resuming devices synchronously
when user space changes the runtime PM settings for them and
improve its error reporting (Rafael Wysocki, Linus Walleij).
- Fix error paths in devfreq drivers (exynos, exynos-ppmu,
exynos-bus) and in the core, make some devfreq code explicitly
non-modular and change some of it into tristate (Bartlomiej
Zolnierkiewicz, Peter Chen, Paul Gortmaker).
- Add DT support to the generic PM clocks management code and make it
export some more symbols (Jon Hunter, Paul Gortmaker).
- Make the PCI PM core code slightly more robust against possible
driver errors (Andy Shevchenko).
- Make it possible to change DESTDIR and PREFIX in turbostat (Andy
Shevchenko)"
* tag 'pm-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (89 commits)
Revert "cpufreq: pcc-cpufreq: update default value of cpuinfo_transition_latency"
PM / hibernate: Introduce test_resume mode for hibernation
cpufreq: export cpufreq_driver_resolve_freq()
cpufreq: Disallow ->resolve_freq() for drivers providing ->target_index()
PCI / PM: check all fields in pci_set_platform_pm()
cpufreq: acpi-cpufreq: use cached frequency mapping when possible
cpufreq: schedutil: map raw required frequency to driver frequency
cpufreq: add cpufreq_driver_resolve_freq()
cpufreq: intel_pstate: Check cpuid for MSR_HWP_INTERRUPT
intel_pstate: Update cpu_frequency tracepoint every time
cpufreq: intel_pstate: clean remnant struct element
PM / tools: scripts: AnalyzeSuspend v4.2
x86 / hibernate: Use hlt_play_dead() when resuming from hibernation
cpufreq: powernv: Replacing pstate_id with frequency table index
intel_pstate: Fix MSR_CONFIG_TDP_x addressing in core_get_max_pstate()
PM / hibernate: Image data protection during restoration
PM / hibernate: Add missing braces in __register_nosave_region()
PM / hibernate: Clean up comments in snapshot.c
PM / hibernate: Clean up function headers in snapshot.c
PM / hibernate: Add missing braces in hibernate_setup()
...
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Refactoring code to use frequency table index instead of pstate_id.
This abstraction will make the code independent of the pstate values.
- No functional changes
- The highest frequency is at frequency table index 0 and the frequency
decreases as the index increases.
- Macros pstates_to_idx() and idx_to_pstate() can be used for conversion
between pstate_id and index.
- powernv_pstate_info now contains frequency table index to min, max and
nominal frequency (instead of pstate_ids)
- global_pstate_info new stores index values instead pstate ids.
- variables renamed as *_idx which now store index instead of pstate
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Pinned timers must carry the pinned attribute in the timer structure
itself, so convert the code to the new API.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.297014487@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This patch migrates few users of cpufreq tables to the new helpers
that work on sorted freq-tables.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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This routine can't fail unless the frequency table is invalid and
doesn't contain any valid entries.
Make it return the index and WARN() in case it is used for an invalid
table.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The policy already has this pointer set, use it instead.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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When global and local pstate are equal in a powernv_target_index() call,
we don't queue a timer. But we may have timer already queued for future.
This could cause the timer to fire one additional time for no use.
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Fix a WARN_ON caused by smp_call_function_any() when irq is disabled,
because of changes made in the patch ('cpufreq: powernv: Ramp-down
global pstate slower than local-pstate')
https://patchwork.ozlabs.org/patch/612058/
WARNING: CPU: 0 PID: 4 at kernel/smp.c:291
smp_call_function_single+0x170/0x180
Call Trace:
[c0000007f648f9f0] [c0000007f648fa90] 0xc0000007f648fa90 (unreliable)
[c0000007f648fa30] [c0000000001430e0] smp_call_function_any+0x170/0x1c0
[c0000007f648fa90] [c0000000007b4b00]
powernv_cpufreq_target_index+0xe0/0x250
[c0000007f648fb00] [c0000000007ac9dc]
__cpufreq_driver_target+0x20c/0x3d0
[c0000007f648fbc0] [c0000000007b1b4c] od_dbs_timer+0xcc/0x260
[c0000007f648fc10] [c0000000007b3024] dbs_work_handler+0x54/0xa0
[c0000007f648fc50] [c0000000000c49a8] process_one_work+0x1d8/0x590
[c0000007f648fce0] [c0000000000c4e08] worker_thread+0xa8/0x660
[c0000007f648fd80] [c0000000000cca88] kthread+0x108/0x130
[c0000007f648fe30] [c0000000000095e8] ret_from_kernel_thread+0x5c/0x74
- Calling smp_call_function_any() with interrupt disabled (through
spin_lock_irqsave) could cause a deadlock, as smp_call_function_any()
relies on the IPI to complete. This is detected in the
smp_call_function_any() call and hence the WARN_ON.
- As the spinlock (gpstates->lock) is only used to synchronize access of
global_pstate_info between timer irq handler and target_index calls. And
the timer irq handler just try_locks() hence it would not cause a
deadlock. Hence could do without making spinlocks irq safe.
- As the smp_call_function_any() is a blocking call and does not access
global_pstates_info, it could reduce the critcal section by moving
smp_call_function_any() after giving up the lock.
Reported-by: Abdul Haleem <abdhalee@linux.vnet.linux.com>
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
The frequency transition latency from pmin to pmax is observed to be in
few millisecond granurality. And it usually happens to take a performance
penalty during sudden frequency rampup requests.
This patch set solves this problem by using an entity called "global
pstates". The global pstate is a Chip-level entity, so the global entitiy
(Voltage) is managed across the cores. The local pstate is a Core-level
entity, so the local entity (frequency) is managed across threads.
This patch brings down global pstate at a slower rate than the local
pstate. Hence by holding global pstates higher than local pstate makes
the subsequent rampups faster.
A per policy structure is maintained to keep track of the global and
local pstate changes. The global pstate is brought down using a parabolic
equation. The ramp down time to pmin is set to ~5 seconds. To make sure
that the global pstates are dropped at regular interval , a timer is
queued for every 2 seconds during ramp-down phase, which eventually brings
the pstate down to local pstate.
Iozone results show fairly consistent performance boost.
YCSB on redis shows improved Max latencies in most cases.
Iozone write/rewite test were made with filesizes 200704Kb and 401408Kb
with different record sizes . The following table shows IOoperations/sec
with and without patch.
Iozone Results ( in op/sec) ( mean over 3 iterations )
---------------------------------------------------------------------
file size- with without %
recordsize-IOtype patch patch change
----------------------------------------------------------------------
200704-1-SeqWrite 1616532 1615425 0.06
200704-1-Rewrite 2423195 2303130 5.21
200704-2-SeqWrite 1628577 1602620 1.61
200704-2-Rewrite 2428264 2312154 5.02
200704-4-SeqWrite 1617605 1617182 0.02
200704-4-Rewrite 2430524 2351238 3.37
200704-8-SeqWrite 1629478 1600436 1.81
200704-8-Rewrite 2415308 2298136 5.09
200704-16-SeqWrite 1619632 1618250 0.08
200704-16-Rewrite 2396650 2352591 1.87
200704-32-SeqWrite 1632544 1598083 2.15
200704-32-Rewrite 2425119 2329743 4.09
200704-64-SeqWrite 1617812 1617235 0.03
200704-64-Rewrite 2402021 2321080 3.48
200704-128-SeqWrite 1631998 1600256 1.98
200704-128-Rewrite 2422389 2304954 5.09
200704-256 SeqWrite 1617065 1616962 0.00
200704-256-Rewrite 2432539 2301980 5.67
200704-512-SeqWrite 1632599 1598656 2.12
200704-512-Rewrite 2429270 2323676 4.54
200704-1024-SeqWrite 1618758 1616156 0.16
200704-1024-Rewrite 2431631 2315889 4.99
401408-1-SeqWrite 1631479 1608132 1.45
401408-1-Rewrite 2501550 2459409 1.71
401408-2-SeqWrite 1617095 1626069 -0.55
401408-2-Rewrite 2507557 2443621 2.61
401408-4-SeqWrite 1629601 1611869 1.10
401408-4-Rewrite 2505909 2462098 1.77
401408-8-SeqWrite 1617110 1626968 -0.60
401408-8-Rewrite 2512244 2456827 2.25
401408-16-SeqWrite 1632609 1609603 1.42
401408-16-Rewrite 2500792 2451405 2.01
401408-32-SeqWrite 1619294 1628167 -0.54
401408-32-Rewrite 2510115 2451292 2.39
401408-64-SeqWrite 1632709 1603746 1.80
401408-64-Rewrite 2506692 2433186 3.02
401408-128-SeqWrite 1619284 1627461 -0.50
401408-128-Rewrite 2518698 2453361 2.66
401408-256-SeqWrite 1634022 1610681 1.44
401408-256-Rewrite 2509987 2446328 2.60
401408-512-SeqWrite 1617524 1628016 -0.64
401408-512-Rewrite 2504409 2442899 2.51
401408-1024-SeqWrite 1629812 1611566 1.13
401408-1024-Rewrite 2507620 2442968 2.64
Tested with YCSB workload (50% update + 50% read) over redis for 1 million
records and 1 million operation. Each test was carried out with target
operations per second and persistence disabled.
Max-latency (in us)( mean over 5 iterations )
---------------------------------------------------------------
op/s Operation with patch without patch %change
---------------------------------------------------------------
15000 Read 61480.6 50261.4 22.32
15000 cleanup 215.2 293.6 -26.70
15000 update 25666.2 25163.8 2.00
25000 Read 32626.2 89525.4 -63.56
25000 cleanup 292.2 263.0 11.10
25000 update 32293.4 90255.0 -64.22
35000 Read 34783.0 33119.0 5.02
35000 cleanup 321.2 395.8 -18.8
35000 update 36047.0 38747.8 -6.97
40000 Read 38562.2 42357.4 -8.96
40000 cleanup 371.8 384.6 -3.33
40000 update 27861.4 41547.8 -32.94
45000 Read 42271.0 88120.6 -52.03
45000 cleanup 263.6 383.0 -31.17
45000 update 29755.8 81359.0 -63.43
(test without target op/s)
47659 Read 83061.4 136440.6 -39.12
47659 cleanup 195.8 193.8 1.03
47659 update 73429.4 124971.8 -41.24
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
commit 1b0289848d5d ("cpufreq: powernv: Add sysfs attributes to show
throttle stats") used policy->driver_data as a flag for one-time creation
of throttle sysfs files. Instead of this use 'kernfs_find_and_get()' to
check if the attribute already exists. This is required as
policy->driver_data is used for other purposes in the later patch.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Create sysfs attributes to export throttle information in
/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats directory. The
newly added sysfs files are as follows:
1)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/turbo_stat
2)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/sub-turbo_stat
3)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/unthrottle
4)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/powercap
5)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overtemp
6)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/supply_fault
7)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overcurrent
8)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/occ_reset
Detailed explanation of each attribute is added to
Documentation/ABI/testing/sysfs-devices-system-cpu
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Commit 96c4726f01cd "cpufreq: powernv: Remove cpu_to_chip_id() from
hot-path" introduced a 'core_to_chip_map' array to cache the chip-ids
of all cores.
Replace this with a per-CPU variable that stores the pointer to the
chip-array. This removes the linear lookup and provides a neater and
simpler solution.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Unregister the notifiers if cpufreq_driver_register() fails in
powernv_cpufreq_init(). Re-arrange the unregistration and cleanup routines
in powernv_cpufreq_exit() to free all the resources after the driver
has unregistered.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Currently we use printk message to notify the throttle event. But this
can flood the console if the cpu is throttled frequently. So replace the
printk with the tracepoint to notify the throttle event. And also events
like throttle below nominal frequency and OCC_RESET are reduced to
pr_warn/pr_warn_once as pointed by MFG to not mark them as critical
messages. This patch adds 'throttle_reason' to struct chip to store the
throttle reason.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
cpu_to_chip_id() does a DT walk through to find out the chip id by
taking a contended device tree lock. This adds an unnecessary overhead
in a hot path. So instead of calling cpu_to_chip_id() everytime cache
the chip ids for all cores in the array 'core_to_chip_map' and use it
in the hotpath.
Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
In the kworker_thread powernv_cpufreq_work_fn(), we can end up
sending an IPI to a cpu going offline. This is a rare corner case
which is fixed using {get/put}_online_cpus(). Along with this fix,
this patch adds changes to do oneshot cpumask_{clear/and} operation.
Suggested-by: Shreyas B Prabhu <shreyas@linux.vnet.ibm.com>
Suggested-by: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
This will free the dynamically allocated memory of 'chips' on
module exit.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Long ago, only in the lab, there was OPALv1 and OPALv2. Now there is
just OPALv3, with nobody ever expecting anything on pre-OPALv3 to
be cared about or supported by mainline kernels.
So, let's remove FW_FEATURE_OPALv3 and instead use FW_FEATURE_OPAL
exclusively.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
|
|
Log a 'critical' message if the max frequency is reduced below nominal
frequency. We already log 'info' message if the max frequency is
capped below turbo frequency. CPU should guarantee atleast nominal
frequency, but not turbo frequency in all system configurations and
environments. So report the pmax throttling with severity when Pmax is
dipped below nominal frequency.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Modify the OCC reset/load/active event message to make it clearer for
the user to understand the event and effect of the event.
Suggested-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
If frequency is throttled due to OCC reset then cpus will be in Psafe
frequency, so restore the frequency on all cpus to policy->cur when
OCCs are active again. And if frequency is throttled due to Pmax
capping then restore the frequency of all the cpus in the chip on
unthrottling.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
On a reset cycle of OCC, although the system retires from safe
frequency state the local pstate is not restored to Pmin or last
requested pstate. Now if the cpufreq governor initiates a pstate
change, the local pstate will be in Psafe and we will be reporting a
false positive when we are not throttled.
So in powernv_cpufreq_throttle_check() remove the condition which
checks if local pstate is less than Pmin while checking for Psafe
frequency. If the cpus are forced to Psafe then PMSR.psafe_mode_active
bit will be set. So, when OCCs become active this bit will be cleared.
Let us just rely on this bit for reporting throttling.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Re-evaluate the chip's throttled state on recieving OCC_THROTTLE
notification by executing *throttle_check() on any one of the cpu on
the chip. This is a sanity check to verify if we were indeed
throttled/unthrottled after receiving OCC_THROTTLE notification.
We cannot call *throttle_check() directly from the notification
handler because we could be handling chip1's notification in chip2. So
initiate an smp_call to execute *throttle_check(). We are irq-disabled
in the notification handler, so use a worker thread to smp_call
throttle_check() on any of the cpu in the chipmask.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
OCC is an On-Chip-Controller which takes care of power and thermal
safety of the chip. During runtime due to power failure or
overtemperature the OCC may throttle the frequencies of the CPUs to
remain within the power budget.
We want the cpufreq driver to be aware of such situations to be able
to report the reason to the user. We register to opal_message_notifier
to receive OCC messages from opal.
powernv_cpufreq_throttle_check() reports any frequency throttling and
this patch will report the reason or event that caused throttling. We
can be throttled if OCC is reset or OCC limits Pmax due to power or
thermal reasons. We are also notified of unthrottling after an OCC
reset or if OCC restores Pmax on the chip.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
The On-Chip-Controller(OCC) can throttle cpu frequency by reducing the
max allowed frequency for that chip if the chip exceeds its power or
temperature limits. As Pmax capping is a chip level condition report
this throttling behavior at chip level and also do not set the global
'throttled' on Pmax capping instead set the per-chip throttled
variable. Report unthrottling if Pmax is restored after throttling.
This patch adds a structure to store chip id and throttled state of
the chip.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
The power and thermal safety of the system is taken care by an
On-Chip-Controller (OCC) which is real-time subsystem embedded within
the POWER8 processor. OCC continuously monitors the memory and core
temperature, the total system power, state of power supply and fan.
The cpu frequency can be throttled by OCC for the following reasons:
1)If a processor crosses its power and temperature limit then OCC will
lower its Pmax to reduce the frequency and voltage.
2)If OCC crashes then the system is forced to Psafe frequency.
3)If OCC fails to recover then the kernel is not allowed to do any
further frequency changes and the chip will remain in Psafe.
The user can see a drop in performance when frequency is throttled and
is unaware of throttling. So detect and report such a condition, so
the user can check the OCC status to reboot the system or check for
power supply or fan failures.
The current status of the core is read from Power Management Status
Register(PMSR) to check if any of the throttling condition is occurred
and the appropriate throttling message is reported.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
This patch ensures the cpus to kexec/reboot at nominal frequency.
Nominal frequency is the highest cpu frequency on PowerPC at
which the cores can run without getting throttled.
If the host kernel had set the cpus to a low pstate and then it
kexecs/reboots to a cpufreq disabled kernel it would cause the target
kernel to perform poorly. It will also increase the boot up time of
the target kernel. So set the cpus to high pstate, in this case to
nominal frequency before rebooting to avoid such scenarios.
The reboot notifier will set the cpus to nominal frequncy.
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
policy->cpus to minimum
Its possible today that the pstate of a core is held at a high even after the
entire core is hotplugged out if a load had just run on the hotplugged cpu. This is
fair, since it is assumed that the pstate does not matter to a cpu in a deep idle
state, which is the expected state of a hotplugged core on powerpc. However on powerpc,
the pstate at a socket level is held at the maximum of the pstates of each core. Even
if the pstates of the active cores on that socket is low, the socket pstate is held
high due to the pstate of the hotplugged core in the above mentioned scenario. This
can cost significant amount of power loss for no good.
Besides, since it is a non active core, nothing can be done from the kernel's end
to set the frequency of the core right. Hence make use of the stop_cpu callback
to explicitly set the pstate of the core to a minimum when the last cpu of the
core gets hotplugged out.
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Cpufreq depends on platform firmware to implement PStates. In case of
platform firmware failure, cpufreq should not panic host kernel with
BUG_ON(). Less severe pr_warn() will suffice.
Add firmware_has_feature(FW_FEATURE_OPALv3) check to
skip probing for device-tree on non-powernv platforms.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
|
|
powernv_cpufreq_get() is only referenced in this file.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org> on V2.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Paul Gortmaker reported the following build failure of the powernv cpufreq
driver on UP configs:
drivers/cpufreq/powernv-cpufreq.c:241:2: error: implicit declaration of
function 'cpu_sibling_mask' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[3]: *** [drivers/cpufreq/powernv-cpufreq.o] Error 1
make[2]: *** [drivers/cpufreq] Error 2
make[1]: *** [drivers] Error 2
make: *** [sub-make] Error 2
The trouble here is that cpu_sibling_mask is defined only in <asm/smp.h>,
and <linux/smp.h> includes <asm/smp.h> only in SMP builds.
So fix this build failure by explicitly including <asm/smp.h> in the driver,
so that we get the definition of cpu_sibling_mask even in UP configurations.
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
The .driver_data field in the cpufreq_frequency_table was supposed to
be private to the drivers. However at some later point, it was being
used to indicate if the particular frequency in the table is the
BOOST_FREQUENCY. After patches [1] and [2], the .driver_data is once
again private to the driver. Thus we can safely use
cpufreq_frequency_table.driver_data to store pstate_ids instead of
having to maintain a separate array powernv_pstate_ids[] for this
purpose.
[1]:
Subject: cpufreq: don't print value of .driver_data from core
From : Viresh Kumar <viresh.kumar@ linaro.org>
url : http://marc.info/?l=linux-pm&m=139601421504709&w=2
[2]:
Subject: cpufreq: create another field .flags in cpufreq_frequency_table
From : Viresh Kumar <viresh.kumar@linaro.org>
url : http://marc.info/?l=linux-pm&m=139601416804702&w=2
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Backend driver to dynamically set voltage and frequency on
IBM POWER non-virtualized platforms. Power management SPRs
are used to set the required PState.
This driver works in conjunction with cpufreq governors
like 'ondemand' to provide a demand based frequency and
voltage setting on IBM POWER non-virtualized platforms.
PState table is obtained from OPAL v3 firmware through device
tree.
powernv_cpufreq back-end driver would parse the relevant device-tree
nodes and initialise the cpufreq subsystem on powernv platform.
The code was originally written by svaidy@linux.vnet.ibm.com. Over
time it was modified to accomodate bug-fixes as well as updates to the
the cpu-freq core. Relevant portions of the change logs corresponding
to those modifications are noted below:
* The policy->cpus needs to be populated in a hotplug-invariant
manner instead of using cpu_sibling_mask() which varies with
cpu-hotplug. This is because the cpufreq core code copies this
content into policy->related_cpus mask which should not vary on
cpu-hotplug. [Authored by srivatsa.bhat@linux.vnet.ibm.com]
* Create a helper routine that can return the cpu-frequency for the
corresponding pstate_id. Also, cache the values of the pstate_max,
pstate_min and pstate_nominal and nr_pstates in a static structure
so that they can be reused in the future to perform any
validations. [Authored by ego@linux.vnet.ibm.com]
* Create a driver attribute named cpuinfo_nominal_freq which creates
a sysfs read-only file named cpuinfo_nominal_freq. Export the
frequency corresponding to the nominal_pstate through this
interface.
Nominal frequency is the highest non-turbo frequency for the
platform. This is generally used for setting governor policies
from user space for optimal energy efficiency. [Authored by
ego@linux.vnet.ibm.com]
* Implement a powernv_cpufreq_get(unsigned int cpu) method which will
return the current operating frequency. Export this via the sysfs
interface cpuinfo_cur_freq by setting powernv_cpufreq_driver.get to
powernv_cpufreq_get(). [Authored by ego@linux.vnet.ibm.com]
[Change log updated by ego@linux.vnet.ibm.com]
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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