path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-12 13:14:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-12 13:14:19 -0700
commit19c1940feab777bb037c665a09f495d08a6c4e6c (patch)
tree68d4de31f30c9d69a1f1ea080b8a69ce61e1ead5 /Documentation
parent7c574cf6aeb75920ba4d3af937bb1b3c42785ac4 (diff)
parentd715a226b0b3dae48865d05e8c36175a8f75a809 (diff)
Merge tag 'pm+acpi-3.16-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more ACPI and power management updates from Rafael Wysocki: "These are fixups on top of the previous PM+ACPI pull request, regression fixes (ACPI hotplug, cpufreq ppc-corenet), other bug fixes (ACPI reset, cpufreq), new PM trace points for system suspend profiling and a copyright notice update. Specifics: - I didn't remember correctly that the Hans de Goede's ACPI video patches actually didn't flip the video.use_native_backlight default, although we had discussed that and decided to do that. Since I said we would do that in the previous PM+ACPI pull request, make that change for real now. - ACPI bus check notifications for PCI host bridges don't cause the bus below the host bridge to be checked for changes as they should because of a mistake in the ACPI-based PCI hotplug (ACPIPHP) subsystem that forgets to add hotplug contexts to PCI host bridge ACPI device objects. Create hotplug contexts for PCI host bridges too as appropriate. - Revert recent cpufreq commit related to the big.LITTLE cpufreq driver that breaks arm64 builds. - Fix for a regression in the ppc-corenet cpufreq driver introduced during the 3.15 cycle and causing the driver to use the remainder from do_div instead of the quotient. From Ed Swarthout. - Resets triggered by panic activate a BUG_ON() in vmalloc.c on systems where the ACPI reset register is located in memory address space. Fix from Randy Wright. - Fix for a problem with cpufreq governors that decisions made by them may be suboptimal due to the fact that deferrable timers are used by them for CPU load sampling. From Srivatsa S Bhat. - Fix for a problem with the Tegra cpufreq driver where the CPU frequency is temporarily switched to a "stable" level that is different from both the initial and target frequencies during transitions which causes udelay() to expire earlier than it should sometimes. From Viresh Kumar. - New trace points and rework of some existing trace points for system suspend/resume profiling from Todd Brandt. - Assorted cpufreq fixes and cleanups from Stratos Karafotis and Viresh Kumar. - Copyright notice update for suspend-and-cpuhotplug.txt from Srivatsa S Bhat" * tag 'pm+acpi-3.16-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI / hotplug / PCI: Add hotplug contexts to PCI host bridges PM / sleep: trace events for device PM callbacks cpufreq: cpufreq-cpu0: remove dependency on THERMAL and REGULATOR cpufreq: tegra: update comment for clarity cpufreq: intel_pstate: Remove duplicate CPU ID check cpufreq: Mark CPU0 driver with CPUFREQ_NEED_INITIAL_FREQ_CHECK flag PM / Documentation: Update copyright in suspend-and-cpuhotplug.txt cpufreq: governor: remove copy_prev_load from 'struct cpu_dbs_common_info' cpufreq: governor: Be friendly towards latency-sensitive bursty workloads PM / sleep: trace events for suspend/resume cpufreq: ppc-corenet-cpu-freq: do_div use quotient Revert "cpufreq: Enable big.LITTLE cpufreq driver on arm64" cpufreq: Tegra: implement intermediate frequency callbacks cpufreq: add support for intermediate (stable) frequencies ACPI / video: Change the default for video.use_native_backlight to 1 ACPI: Fix bug when ACPI reset register is implemented in system memory
Diffstat (limited to 'Documentation')
2 files changed, 28 insertions, 3 deletions
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index b045fe54986a..14f4e6336d88 100644
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -26,6 +26,7 @@ Contents:
1.4 target/target_index or setpolicy?
1.5 target/target_index
1.6 setpolicy
+1.7 get_intermediate and target_intermediate
2. Frequency Table Helpers
@@ -79,6 +80,10 @@ cpufreq_driver.attr - A pointer to a NULL-terminated list of
"struct freq_attr" which allow to
export values to sysfs.
+and target_intermediate Used to switch to stable frequency while
+ changing CPU frequency.
1.2 Per-CPU Initialization
@@ -151,7 +156,7 @@ Some cpufreq-capable processors switch the frequency between certain
limits on their own. These shall use the ->setpolicy call
-1.4. target/target_index
+1.5. target/target_index
The target_index call has two arguments: struct cpufreq_policy *policy,
@@ -160,6 +165,9 @@ and unsigned int index (into the exposed frequency table).
The CPUfreq driver must set the new frequency when called here. The
actual frequency must be determined by freq_table[index].frequency.
+It should always restore to earlier frequency (i.e. policy->restore_freq) in
+case of errors, even if we switched to intermediate frequency earlier.
The target call has three arguments: struct cpufreq_policy *policy,
@@ -179,7 +187,7 @@ Here again the frequency table helper might assist you - see section 2
for details.
-1.5 setpolicy
+1.6 setpolicy
The setpolicy call only takes a struct cpufreq_policy *policy as
@@ -190,6 +198,23 @@ setting when policy->policy is CPUFREQ_POLICY_PERFORMANCE, and a
powersaving-oriented setting when CPUFREQ_POLICY_POWERSAVE. Also check
the reference implementation in drivers/cpufreq/longrun.c
+1.7 get_intermediate and target_intermediate
+Only for drivers with target_index() and CPUFREQ_ASYNC_NOTIFICATION unset.
+get_intermediate should return a stable intermediate frequency platform wants to
+switch to, and target_intermediate() should set CPU to to that frequency, before
+jumping to the frequency corresponding to 'index'. Core will take care of
+sending notifications and driver doesn't have to handle them in
+target_intermediate() or target_index().
+Drivers can return '0' from get_intermediate() in case they don't wish to switch
+to intermediate frequency for some target frequency. In that case core will
+directly call ->target_index().
+NOTE: ->target_index() should restore to policy->restore_freq in case of
+failures as core would send notifications for that.
2. Frequency Table Helpers
diff --git a/Documentation/power/suspend-and-cpuhotplug.txt b/Documentation/power/suspend-and-cpuhotplug.txt
index e13dafc8e8f1..2850df3bf957 100644
--- a/Documentation/power/suspend-and-cpuhotplug.txt
+++ b/Documentation/power/suspend-and-cpuhotplug.txt
@@ -1,6 +1,6 @@
Interaction of Suspend code (S3) with the CPU hotplug infrastructure
- (C) 2011 Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
+ (C) 2011 - 2014 Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
I. How does the regular CPU hotplug code differ from how the Suspend-to-RAM

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