summaryrefslogtreecommitdiff
path: root/Documentation
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2021-06-29 23:36:06 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-29 23:36:06 +0300
commit3563f55ce65462063543dfa6a8d8c7fbfb9d7772 (patch)
treef43239057f966f6511e360930071e02b72f72297 /Documentation
parent1dfb0f47aca11350f45f8c04c3b83f0e829adfa9 (diff)
parent22b65d31ad9d10cdd726239966b6d6f67db8f251 (diff)
downloadlinux-3563f55ce65462063543dfa6a8d8c7fbfb9d7772.tar.xz
Merge tag 'pm-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki: "These add hybrid processors support to the intel_pstate driver and make it work with more processor models when HWP is disabled, make the intel_idle driver use special C6 idle state paremeters when package C-states are disabled, add cooling support to the tegra30 devfreq driver, rework the TEO (timer events oriented) cpuidle governor, extend the OPP (operating performance points) framework to use the required-opps DT property in more cases, fix some issues and clean up a number of assorted pieces of code. Specifics: - Make intel_pstate support hybrid processors using abstract performance units in the HWP interface (Rafael Wysocki). - Add Icelake servers and Cometlake support in no-HWP mode to intel_pstate (Giovanni Gherdovich). - Make cpufreq_online() error path be consistent with the CPU device removal path in cpufreq (Rafael Wysocki). - Clean up 3 cpufreq drivers and the statistics code (Hailong Liu, Randy Dunlap, Shaokun Zhang). - Make intel_idle use special idle state parameters for C6 when package C-states are disabled (Chen Yu). - Rework the TEO (timer events oriented) cpuidle governor to address some theoretical shortcomings in it (Rafael Wysocki). - Drop unneeded semicolon from the TEO governor (Wan Jiabing). - Modify the runtime PM framework to accept unassigned suspend and resume callback pointers (Ulf Hansson). - Improve pm_runtime_get_sync() documentation (Krzysztof Kozlowski). - Improve device performance states support in the generic power domains (genpd) framework (Ulf Hansson). - Fix some documentation issues in genpd (Yang Yingliang). - Make the operating performance points (OPP) framework use the required-opps DT property in use cases that are not related to genpd (Hsin-Yi Wang). - Make lazy_link_required_opp_table() use list_del_init instead of list_del/INIT_LIST_HEAD (Yang Yingliang). - Simplify wake IRQs handling in the core system-wide sleep support code and clean up some coding style inconsistencies in it (Tian Tao, Zhen Lei). - Add cooling support to the tegra30 devfreq driver and improve its DT bindings (Dmitry Osipenko). - Fix some assorted issues in the devfreq core and drivers (Chanwoo Choi, Dong Aisheng, YueHaibing)" * tag 'pm-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (39 commits) PM / devfreq: passive: Fix get_target_freq when not using required-opp cpufreq: Make cpufreq_online() call driver->offline() on errors opp: Allow required-opps to be used for non genpd use cases cpuidle: teo: remove unneeded semicolon in teo_select() dt-bindings: devfreq: tegra30-actmon: Add cooling-cells dt-bindings: devfreq: tegra30-actmon: Convert to schema PM / devfreq: userspace: Use DEVICE_ATTR_RW macro PM: runtime: Clarify documentation when callbacks are unassigned PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks PM: runtime: Improve path in rpm_idle() when no callback PM: hibernate: remove leading spaces before tabs PM: sleep: remove trailing spaces and tabs PM: domains: Drop/restore performance state votes for devices at runtime PM PM: domains: Return early if perf state is already set for the device PM: domains: Split code in dev_pm_genpd_set_performance_state() cpuidle: teo: Use kerneldoc documentation in admin-guide cpuidle: teo: Rework most recent idle duration values treatment cpuidle: teo: Change the main idle state selection logic cpuidle: teo: Cosmetic modification of teo_select() cpuidle: teo: Cosmetic modifications of teo_update() ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/pm/cpuidle.rst77
-rw-r--r--Documentation/admin-guide/pm/intel_pstate.rst6
-rw-r--r--Documentation/devicetree/bindings/arm/tegra/nvidia,tegra30-actmon.txt57
-rw-r--r--Documentation/devicetree/bindings/devfreq/nvidia,tegra30-actmon.yaml126
-rw-r--r--Documentation/power/runtime_pm.rst15
5 files changed, 148 insertions, 133 deletions
diff --git a/Documentation/admin-guide/pm/cpuidle.rst b/Documentation/admin-guide/pm/cpuidle.rst
index 10fde58d0869..aec2cd2aaea7 100644
--- a/Documentation/admin-guide/pm/cpuidle.rst
+++ b/Documentation/admin-guide/pm/cpuidle.rst
@@ -347,81 +347,8 @@ for tickless systems. It follows the same basic strategy as the ``menu`` `one
<menu-gov_>`_: it always tries to find the deepest idle state suitable for the
given conditions. However, it applies a different approach to that problem.
-First, it does not use sleep length correction factors, but instead it attempts
-to correlate the observed idle duration values with the available idle states
-and use that information to pick up the idle state that is most likely to
-"match" the upcoming CPU idle interval. Second, it does not take the tasks
-that were running on the given CPU in the past and are waiting on some I/O
-operations to complete now at all (there is no guarantee that they will run on
-the same CPU when they become runnable again) and the pattern detection code in
-it avoids taking timer wakeups into account. It also only uses idle duration
-values less than the current time till the closest timer (with the scheduler
-tick excluded) for that purpose.
-
-Like in the ``menu`` governor `case <menu-gov_>`_, the first step is to obtain
-the *sleep length*, which is the time until the closest timer event with the
-assumption that the scheduler tick will be stopped (that also is the upper bound
-on the time until the next CPU wakeup). That value is then used to preselect an
-idle state on the basis of three metrics maintained for each idle state provided
-by the ``CPUIdle`` driver: ``hits``, ``misses`` and ``early_hits``.
-
-The ``hits`` and ``misses`` metrics measure the likelihood that a given idle
-state will "match" the observed (post-wakeup) idle duration if it "matches" the
-sleep length. They both are subject to decay (after a CPU wakeup) every time
-the target residency of the idle state corresponding to them is less than or
-equal to the sleep length and the target residency of the next idle state is
-greater than the sleep length (that is, when the idle state corresponding to
-them "matches" the sleep length). The ``hits`` metric is increased if the
-former condition is satisfied and the target residency of the given idle state
-is less than or equal to the observed idle duration and the target residency of
-the next idle state is greater than the observed idle duration at the same time
-(that is, it is increased when the given idle state "matches" both the sleep
-length and the observed idle duration). In turn, the ``misses`` metric is
-increased when the given idle state "matches" the sleep length only and the
-observed idle duration is too short for its target residency.
-
-The ``early_hits`` metric measures the likelihood that a given idle state will
-"match" the observed (post-wakeup) idle duration if it does not "match" the
-sleep length. It is subject to decay on every CPU wakeup and it is increased
-when the idle state corresponding to it "matches" the observed (post-wakeup)
-idle duration and the target residency of the next idle state is less than or
-equal to the sleep length (i.e. the idle state "matching" the sleep length is
-deeper than the given one).
-
-The governor walks the list of idle states provided by the ``CPUIdle`` driver
-and finds the last (deepest) one with the target residency less than or equal
-to the sleep length. Then, the ``hits`` and ``misses`` metrics of that idle
-state are compared with each other and it is preselected if the ``hits`` one is
-greater (which means that that idle state is likely to "match" the observed idle
-duration after CPU wakeup). If the ``misses`` one is greater, the governor
-preselects the shallower idle state with the maximum ``early_hits`` metric
-(or if there are multiple shallower idle states with equal ``early_hits``
-metric which also is the maximum, the shallowest of them will be preselected).
-[If there is a wakeup latency constraint coming from the `PM QoS framework
-<cpu-pm-qos_>`_ which is hit before reaching the deepest idle state with the
-target residency within the sleep length, the deepest idle state with the exit
-latency within the constraint is preselected without consulting the ``hits``,
-``misses`` and ``early_hits`` metrics.]
-
-Next, the governor takes several idle duration values observed most recently
-into consideration and if at least a half of them are greater than or equal to
-the target residency of the preselected idle state, that idle state becomes the
-final candidate to ask for. Otherwise, the average of the most recent idle
-duration values below the target residency of the preselected idle state is
-computed and the governor walks the idle states shallower than the preselected
-one and finds the deepest of them with the target residency within that average.
-That idle state is then taken as the final candidate to ask for.
-
-Still, at this point the governor may need to refine the idle state selection if
-it has not decided to `stop the scheduler tick <idle-cpus-and-tick_>`_. That
-generally happens if the target residency of the idle state selected so far is
-less than the tick period and the tick has not been stopped already (in a
-previous iteration of the idle loop). Then, like in the ``menu`` governor
-`case <menu-gov_>`_, the sleep length used in the previous computations may not
-reflect the real time until the closest timer event and if it really is greater
-than that time, a shallower state with a suitable target residency may need to
-be selected.
-
+.. kernel-doc:: drivers/cpuidle/governors/teo.c
+ :doc: teo-description
.. _idle-states-representation:
diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst
index 7a7d4b041eac..d5043cd8d2f5 100644
--- a/Documentation/admin-guide/pm/intel_pstate.rst
+++ b/Documentation/admin-guide/pm/intel_pstate.rst
@@ -365,6 +365,9 @@ argument is passed to the kernel in the command line.
inclusive) including both turbo and non-turbo P-states (see
`Turbo P-states Support`_).
+ This attribute is present only if the value exposed by it is the same
+ for all of the CPUs in the system.
+
The value of this attribute is not affected by the ``no_turbo``
setting described `below <no_turbo_attr_>`_.
@@ -374,6 +377,9 @@ argument is passed to the kernel in the command line.
Ratio of the `turbo range <turbo_>`_ size to the size of the entire
range of supported P-states, in percent.
+ This attribute is present only if the value exposed by it is the same
+ for all of the CPUs in the system.
+
This attribute is read-only.
.. _no_turbo_attr:
diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra30-actmon.txt b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra30-actmon.txt
deleted file mode 100644
index 897eedfa2bc8..000000000000
--- a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra30-actmon.txt
+++ /dev/null
@@ -1,57 +0,0 @@
-NVIDIA Tegra Activity Monitor
-
-The activity monitor block collects statistics about the behaviour of other
-components in the system. This information can be used to derive the rate at
-which the external memory needs to be clocked in order to serve all requests
-from the monitored clients.
-
-Required properties:
-- compatible: should be "nvidia,tegra<chip>-actmon"
-- reg: offset and length of the register set for the device
-- interrupts: standard interrupt property
-- clocks: Must contain a phandle and clock specifier pair for each entry in
-clock-names. See ../../clock/clock-bindings.txt for details.
-- clock-names: Must include the following entries:
- - actmon
- - emc
-- resets: Must contain an entry for each entry in reset-names. See
-../../reset/reset.txt for details.
-- reset-names: Must include the following entries:
- - actmon
-- operating-points-v2: See ../bindings/opp/opp.txt for details.
-- interconnects: Should contain entries for memory clients sitting on
- MC->EMC memory interconnect path.
-- interconnect-names: Should include name of the interconnect path for each
- interconnect entry. Consult TRM documentation for
- information about available memory clients, see MEMORY
- CONTROLLER section.
-
-For each opp entry in 'operating-points-v2' table:
-- opp-supported-hw: bitfield indicating SoC speedo ID mask
-- opp-peak-kBps: peak bandwidth of the memory channel
-
-Example:
- dfs_opp_table: opp-table {
- compatible = "operating-points-v2";
-
- opp@12750000 {
- opp-hz = /bits/ 64 <12750000>;
- opp-supported-hw = <0x000F>;
- opp-peak-kBps = <51000>;
- };
- ...
- };
-
- actmon@6000c800 {
- compatible = "nvidia,tegra124-actmon";
- reg = <0x0 0x6000c800 0x0 0x400>;
- interrupts = <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH>;
- clocks = <&tegra_car TEGRA124_CLK_ACTMON>,
- <&tegra_car TEGRA124_CLK_EMC>;
- clock-names = "actmon", "emc";
- resets = <&tegra_car 119>;
- reset-names = "actmon";
- operating-points-v2 = <&dfs_opp_table>;
- interconnects = <&mc TEGRA124_MC_MPCORER &emc>;
- interconnect-names = "cpu";
- };
diff --git a/Documentation/devicetree/bindings/devfreq/nvidia,tegra30-actmon.yaml b/Documentation/devicetree/bindings/devfreq/nvidia,tegra30-actmon.yaml
new file mode 100644
index 000000000000..e3379d106728
--- /dev/null
+++ b/Documentation/devicetree/bindings/devfreq/nvidia,tegra30-actmon.yaml
@@ -0,0 +1,126 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/devfreq/nvidia,tegra30-actmon.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NVIDIA Tegra30 Activity Monitor
+
+maintainers:
+ - Dmitry Osipenko <digetx@gmail.com>
+ - Jon Hunter <jonathanh@nvidia.com>
+ - Thierry Reding <thierry.reding@gmail.com>
+
+description: |
+ The activity monitor block collects statistics about the behaviour of other
+ components in the system. This information can be used to derive the rate at
+ which the external memory needs to be clocked in order to serve all requests
+ from the monitored clients.
+
+properties:
+ compatible:
+ enum:
+ - nvidia,tegra30-actmon
+ - nvidia,tegra114-actmon
+ - nvidia,tegra124-actmon
+ - nvidia,tegra210-actmon
+
+ reg:
+ maxItems: 1
+
+ clocks:
+ maxItems: 2
+
+ clock-names:
+ items:
+ - const: actmon
+ - const: emc
+
+ resets:
+ maxItems: 1
+
+ reset-names:
+ items:
+ - const: actmon
+
+ interrupts:
+ maxItems: 1
+
+ interconnects:
+ minItems: 1
+ maxItems: 12
+
+ interconnect-names:
+ minItems: 1
+ maxItems: 12
+ description:
+ Should include name of the interconnect path for each interconnect
+ entry. Consult TRM documentation for information about available
+ memory clients, see MEMORY CONTROLLER and ACTIVITY MONITOR sections.
+
+ operating-points-v2:
+ description:
+ Should contain freqs and voltages and opp-supported-hw property, which
+ is a bitfield indicating SoC speedo ID mask.
+
+ "#cooling-cells":
+ const: 2
+
+required:
+ - compatible
+ - reg
+ - clocks
+ - clock-names
+ - resets
+ - reset-names
+ - interrupts
+ - interconnects
+ - interconnect-names
+ - operating-points-v2
+ - "#cooling-cells"
+
+additionalProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/memory/tegra30-mc.h>
+
+ mc: memory-controller@7000f000 {
+ compatible = "nvidia,tegra30-mc";
+ reg = <0x7000f000 0x400>;
+ clocks = <&clk 32>;
+ clock-names = "mc";
+
+ interrupts = <0 77 4>;
+
+ #iommu-cells = <1>;
+ #reset-cells = <1>;
+ #interconnect-cells = <1>;
+ };
+
+ emc: external-memory-controller@7000f400 {
+ compatible = "nvidia,tegra30-emc";
+ reg = <0x7000f400 0x400>;
+ interrupts = <0 78 4>;
+ clocks = <&clk 57>;
+
+ nvidia,memory-controller = <&mc>;
+ operating-points-v2 = <&dvfs_opp_table>;
+ power-domains = <&domain>;
+
+ #interconnect-cells = <0>;
+ };
+
+ actmon@6000c800 {
+ compatible = "nvidia,tegra30-actmon";
+ reg = <0x6000c800 0x400>;
+ interrupts = <0 45 4>;
+ clocks = <&clk 119>, <&clk 57>;
+ clock-names = "actmon", "emc";
+ resets = <&rst 119>;
+ reset-names = "actmon";
+ operating-points-v2 = <&dvfs_opp_table>;
+ interconnects = <&mc TEGRA30_MC_MPCORER &emc>;
+ interconnect-names = "cpu-read";
+ #cooling-cells = <2>;
+ };
diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst
index 18ae21bf7f92..d6bf84f061f4 100644
--- a/Documentation/power/runtime_pm.rst
+++ b/Documentation/power/runtime_pm.rst
@@ -378,7 +378,11 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
`int pm_runtime_get_sync(struct device *dev);`
- increment the device's usage counter, run pm_runtime_resume(dev) and
- return its result
+ return its result;
+ note that it does not drop the device's usage counter on errors, so
+ consider using pm_runtime_resume_and_get() instead of it, especially
+ if its return value is checked by the caller, as this is likely to
+ result in cleaner code.
`int pm_runtime_get_if_in_use(struct device *dev);`
- return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the
@@ -827,6 +831,15 @@ or driver about runtime power changes. Instead, the driver for the device's
parent must take responsibility for telling the device's driver when the
parent's power state changes.
+Note that, in some cases it may not be desirable for subsystems/drivers to call
+pm_runtime_no_callbacks() for their devices. This could be because a subset of
+the runtime PM callbacks needs to be implemented, a platform dependent PM
+domain could get attached to the device or that the device is power managed
+through a supplier device link. For these reasons and to avoid boilerplate code
+in subsystems/drivers, the PM core allows runtime PM callbacks to be
+unassigned. More precisely, if a callback pointer is NULL, the PM core will act
+as though there was a callback and it returned 0.
+
9. Autosuspend, or automatically-delayed suspends
=================================================