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-rw-r--r--Documentation/driver-api/pm/cpuidle.rst65
1 files changed, 30 insertions, 35 deletions
diff --git a/Documentation/driver-api/pm/cpuidle.rst b/Documentation/driver-api/pm/cpuidle.rst
index 3588bf078566..d477208604b8 100644
--- a/Documentation/driver-api/pm/cpuidle.rst
+++ b/Documentation/driver-api/pm/cpuidle.rst
@@ -1,11 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
.. include:: <isonum.txt>
-.. |struct cpuidle_governor| replace:: :c:type:`struct cpuidle_governor <cpuidle_governor>`
-.. |struct cpuidle_device| replace:: :c:type:`struct cpuidle_device <cpuidle_device>`
-.. |struct cpuidle_driver| replace:: :c:type:`struct cpuidle_driver <cpuidle_driver>`
-.. |struct cpuidle_state| replace:: :c:type:`struct cpuidle_state <cpuidle_state>`
-
========================
CPU Idle Time Management
========================
@@ -54,7 +49,7 @@ platform that the Linux kernel can run on. For this reason, data structures
operated on by them cannot depend on any hardware architecture or platform
design details as well.
-The governor itself is represented by a |struct cpuidle_governor| object
+The governor itself is represented by a struct cpuidle_governor object
containing four callback pointers, :c:member:`enable`, :c:member:`disable`,
:c:member:`select`, :c:member:`reflect`, a :c:member:`rating` field described
below, and a name (string) used for identifying it.
@@ -83,11 +78,11 @@ callbacks:
int (*enable) (struct cpuidle_driver *drv, struct cpuidle_device *dev);
The role of this callback is to prepare the governor for handling the
- (logical) CPU represented by the |struct cpuidle_device| object pointed
- to by the ``dev`` argument. The |struct cpuidle_driver| object pointed
+ (logical) CPU represented by the struct cpuidle_device object pointed
+ to by the ``dev`` argument. The struct cpuidle_driver object pointed
to by the ``drv`` argument represents the ``CPUIdle`` driver to be used
with that CPU (among other things, it should contain the list of
- |struct cpuidle_state| objects representing idle states that the
+ struct cpuidle_state objects representing idle states that the
processor holding the given CPU can be asked to enter).
It may fail, in which case it is expected to return a negative error
@@ -102,7 +97,7 @@ callbacks:
void (*disable) (struct cpuidle_driver *drv, struct cpuidle_device *dev);
Called to make the governor stop handling the (logical) CPU represented
- by the |struct cpuidle_device| object pointed to by the ``dev``
+ by the struct cpuidle_device object pointed to by the ``dev``
argument.
It is expected to reverse any changes made by the ``->enable()``
@@ -116,12 +111,12 @@ callbacks:
bool *stop_tick);
Called to select an idle state for the processor holding the (logical)
- CPU represented by the |struct cpuidle_device| object pointed to by the
+ CPU represented by the struct cpuidle_device object pointed to by the
``dev`` argument.
The list of idle states to take into consideration is represented by the
- :c:member:`states` array of |struct cpuidle_state| objects held by the
- |struct cpuidle_driver| object pointed to by the ``drv`` argument (which
+ :c:member:`states` array of struct cpuidle_state objects held by the
+ struct cpuidle_driver object pointed to by the ``drv`` argument (which
represents the ``CPUIdle`` driver to be used with the CPU at hand). The
value returned by this callback is interpreted as an index into that
array (unless it is a negative error code).
@@ -136,7 +131,7 @@ callbacks:
asking the processor to enter the idle state).
This callback is mandatory (i.e. the :c:member:`select` callback pointer
- in |struct cpuidle_governor| must not be ``NULL`` for the registration
+ in struct cpuidle_governor must not be ``NULL`` for the registration
of the governor to succeed).
:c:member:`reflect`
@@ -167,21 +162,21 @@ CPU idle time management (``CPUIdle``) drivers provide an interface between the
other parts of ``CPUIdle`` and the hardware.
First of all, a ``CPUIdle`` driver has to populate the :c:member:`states` array
-of |struct cpuidle_state| objects included in the |struct cpuidle_driver| object
+of struct cpuidle_state objects included in the struct cpuidle_driver object
representing it. Going forward this array will represent the list of available
idle states that the processor hardware can be asked to enter shared by all of
the logical CPUs handled by the given driver.
The entries in the :c:member:`states` array are expected to be sorted by the
-value of the :c:member:`target_residency` field in |struct cpuidle_state| in
+value of the :c:member:`target_residency` field in struct cpuidle_state in
the ascending order (that is, index 0 should correspond to the idle state with
the minimum value of :c:member:`target_residency`). [Since the
:c:member:`target_residency` value is expected to reflect the "depth" of the
-idle state represented by the |struct cpuidle_state| object holding it, this
+idle state represented by the struct cpuidle_state object holding it, this
sorting order should be the same as the ascending sorting order by the idle
state "depth".]
-Three fields in |struct cpuidle_state| are used by the existing ``CPUIdle``
+Three fields in struct cpuidle_state are used by the existing ``CPUIdle``
governors for computations related to idle state selection:
:c:member:`target_residency`
@@ -203,7 +198,7 @@ governors for computations related to idle state selection:
any idle state at all. [There are other flags used by the ``CPUIdle``
core in special situations.]
-The :c:member:`enter` callback pointer in |struct cpuidle_state|, which must not
+The :c:member:`enter` callback pointer in struct cpuidle_state, which must not
be ``NULL``, points to the routine to execute in order to ask the processor to
enter this particular idle state:
@@ -212,14 +207,14 @@ enter this particular idle state:
void (*enter) (struct cpuidle_device *dev, struct cpuidle_driver *drv,
int index);
-The first two arguments of it point to the |struct cpuidle_device| object
+The first two arguments of it point to the struct cpuidle_device object
representing the logical CPU running this callback and the
-|struct cpuidle_driver| object representing the driver itself, respectively,
-and the last one is an index of the |struct cpuidle_state| entry in the driver's
+struct cpuidle_driver object representing the driver itself, respectively,
+and the last one is an index of the struct cpuidle_state entry in the driver's
:c:member:`states` array representing the idle state to ask the processor to
enter.
-The analogous ``->enter_s2idle()`` callback in |struct cpuidle_state| is used
+The analogous ``->enter_s2idle()`` callback in struct cpuidle_state is used
only for implementing the suspend-to-idle system-wide power management feature.
The difference between in and ``->enter()`` is that it must not re-enable
interrupts at any point (even temporarily) or attempt to change the states of
@@ -227,48 +222,48 @@ clock event devices, which the ``->enter()`` callback may do sometimes.
Once the :c:member:`states` array has been populated, the number of valid
entries in it has to be stored in the :c:member:`state_count` field of the
-|struct cpuidle_driver| object representing the driver. Moreover, if any
+struct cpuidle_driver object representing the driver. Moreover, if any
entries in the :c:member:`states` array represent "coupled" idle states (that
is, idle states that can only be asked for if multiple related logical CPUs are
-idle), the :c:member:`safe_state_index` field in |struct cpuidle_driver| needs
+idle), the :c:member:`safe_state_index` field in struct cpuidle_driver needs
to be the index of an idle state that is not "coupled" (that is, one that can be
asked for if only one logical CPU is idle).
In addition to that, if the given ``CPUIdle`` driver is only going to handle a
subset of logical CPUs in the system, the :c:member:`cpumask` field in its
-|struct cpuidle_driver| object must point to the set (mask) of CPUs that will be
+struct cpuidle_driver object must point to the set (mask) of CPUs that will be
handled by it.
A ``CPUIdle`` driver can only be used after it has been registered. If there
are no "coupled" idle state entries in the driver's :c:member:`states` array,
-that can be accomplished by passing the driver's |struct cpuidle_driver| object
+that can be accomplished by passing the driver's struct cpuidle_driver object
to :c:func:`cpuidle_register_driver()`. Otherwise, :c:func:`cpuidle_register()`
should be used for this purpose.
-However, it also is necessary to register |struct cpuidle_device| objects for
+However, it also is necessary to register struct cpuidle_device objects for
all of the logical CPUs to be handled by the given ``CPUIdle`` driver with the
help of :c:func:`cpuidle_register_device()` after the driver has been registered
and :c:func:`cpuidle_register_driver()`, unlike :c:func:`cpuidle_register()`,
does not do that automatically. For this reason, the drivers that use
:c:func:`cpuidle_register_driver()` to register themselves must also take care
-of registering the |struct cpuidle_device| objects as needed, so it is generally
+of registering the struct cpuidle_device objects as needed, so it is generally
recommended to use :c:func:`cpuidle_register()` for ``CPUIdle`` driver
registration in all cases.
-The registration of a |struct cpuidle_device| object causes the ``CPUIdle``
+The registration of a struct cpuidle_device object causes the ``CPUIdle``
``sysfs`` interface to be created and the governor's ``->enable()`` callback to
be invoked for the logical CPU represented by it, so it must take place after
registering the driver that will handle the CPU in question.
-``CPUIdle`` drivers and |struct cpuidle_device| objects can be unregistered
+``CPUIdle`` drivers and struct cpuidle_device objects can be unregistered
when they are not necessary any more which allows some resources associated with
them to be released. Due to dependencies between them, all of the
-|struct cpuidle_device| objects representing CPUs handled by the given
+struct cpuidle_device objects representing CPUs handled by the given
``CPUIdle`` driver must be unregistered, with the help of
:c:func:`cpuidle_unregister_device()`, before calling
:c:func:`cpuidle_unregister_driver()` to unregister the driver. Alternatively,
:c:func:`cpuidle_unregister()` can be called to unregister a ``CPUIdle`` driver
-along with all of the |struct cpuidle_device| objects representing CPUs handled
+along with all of the struct cpuidle_device objects representing CPUs handled
by it.
``CPUIdle`` drivers can respond to runtime system configuration changes that
@@ -277,8 +272,8 @@ happen, for example, when the system's power source is switched from AC to
battery or the other way around). Upon a notification of such a change,
a ``CPUIdle`` driver is expected to call :c:func:`cpuidle_pause_and_lock()` to
turn ``CPUIdle`` off temporarily and then :c:func:`cpuidle_disable_device()` for
-all of the |struct cpuidle_device| objects representing CPUs affected by that
+all of the struct cpuidle_device objects representing CPUs affected by that
change. Next, it can update its :c:member:`states` array in accordance with
the new configuration of the system, call :c:func:`cpuidle_enable_device()` for
-all of the relevant |struct cpuidle_device| objects and invoke
+all of the relevant struct cpuidle_device objects and invoke
:c:func:`cpuidle_resume_and_unlock()` to allow ``CPUIdle`` to be used again.