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-rw-r--r--Documentation/power/runtime_pm.rst23
1 files changed, 14 insertions, 9 deletions
diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst
index 65b86e487a..5c4e730f38 100644
--- a/Documentation/power/runtime_pm.rst
+++ b/Documentation/power/runtime_pm.rst
@@ -154,7 +154,7 @@ suspending the device are satisfied) and to queue up a suspend request for the
device in that case. If there is no idle callback, or if the callback returns
0, then the PM core will attempt to carry out a runtime suspend of the device,
also respecting devices configured for autosuspend. In essence this means a
-call to pm_runtime_autosuspend() (do note that drivers needs to update the
+call to __pm_runtime_autosuspend() (do note that drivers needs to update the
device last busy mark, pm_runtime_mark_last_busy(), to control the delay under
this circumstance). To prevent this (for example, if the callback routine has
started a delayed suspend), the routine must return a non-zero value. Negative
@@ -396,10 +396,9 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
nonzero, increment the counter and return 1; otherwise return 0 without
changing the counter
- `int pm_runtime_get_if_active(struct device *dev, bool ign_usage_count);`
+ `int pm_runtime_get_if_active(struct device *dev);`
- return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the
- runtime PM status is RPM_ACTIVE, and either ign_usage_count is true
- or the device's usage_count is non-zero, increment the counter and
+ runtime PM status is RPM_ACTIVE, increment the counter and
return 1; otherwise return 0 without changing the counter
`void pm_runtime_put_noidle(struct device *dev);`
@@ -410,6 +409,10 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
pm_request_idle(dev) and return its result
`int pm_runtime_put_autosuspend(struct device *dev);`
+ - does the same as __pm_runtime_put_autosuspend() for now, but in the
+ future, will also call pm_runtime_mark_last_busy() as well, DO NOT USE!
+
+ `int __pm_runtime_put_autosuspend(struct device *dev);`
- decrement the device's usage counter; if the result is 0 then run
pm_request_autosuspend(dev) and return its result
@@ -540,6 +543,7 @@ It is safe to execute the following helper functions from interrupt context:
- pm_runtime_put_noidle()
- pm_runtime_put()
- pm_runtime_put_autosuspend()
+- __pm_runtime_put_autosuspend()
- pm_runtime_enable()
- pm_suspend_ignore_children()
- pm_runtime_set_active()
@@ -730,6 +734,7 @@ out the following operations:
for it, respectively.
7. Generic subsystem callbacks
+==============================
Subsystems may wish to conserve code space by using the set of generic power
management callbacks provided by the PM core, defined in
@@ -865,9 +870,9 @@ automatically be delayed until the desired period of inactivity has elapsed.
Inactivity is determined based on the power.last_busy field. Drivers should
call pm_runtime_mark_last_busy() to update this field after carrying out I/O,
-typically just before calling pm_runtime_put_autosuspend(). The desired length
-of the inactivity period is a matter of policy. Subsystems can set this length
-initially by calling pm_runtime_set_autosuspend_delay(), but after device
+typically just before calling __pm_runtime_put_autosuspend(). The desired
+length of the inactivity period is a matter of policy. Subsystems can set this
+length initially by calling pm_runtime_set_autosuspend_delay(), but after device
registration the length should be controlled by user space, using the
/sys/devices/.../power/autosuspend_delay_ms attribute.
@@ -878,7 +883,7 @@ instead of the non-autosuspend counterparts::
Instead of: pm_runtime_suspend use: pm_runtime_autosuspend;
Instead of: pm_schedule_suspend use: pm_request_autosuspend;
- Instead of: pm_runtime_put use: pm_runtime_put_autosuspend;
+ Instead of: pm_runtime_put use: __pm_runtime_put_autosuspend;
Instead of: pm_runtime_put_sync use: pm_runtime_put_sync_autosuspend.
Drivers may also continue to use the non-autosuspend helper functions; they
@@ -917,7 +922,7 @@ Here is a schematic pseudo-code example::
lock(&foo->private_lock);
if (--foo->num_pending_requests == 0) {
pm_runtime_mark_last_busy(&foo->dev);
- pm_runtime_put_autosuspend(&foo->dev);
+ __pm_runtime_put_autosuspend(&foo->dev);
} else {
foo_process_next_request(foo);
}