Re: [PATCH] PM QoS: update Documentation for the pm_qos and dev_pm_qos frameworks
On Monday, October 03, 2011, jean.pi...@newoldbits.com wrote:
From: Jean Pihet j-pi...@ti.com
Update the documentation for the recently updated pm_qos API, kernel
and user space.
Add the documentation for the per-device PM QoS (dev_pm_qos) framework
API.
Signed-off-by: Jean Pihet j-pi...@ti.com
Applied to linux-pm/pm-qos (and merged into linux-pm/linux-next).
Thanks,
Rafael
---
Documentation/power/pm_qos_interface.txt | 92
--
1 files changed, 87 insertions(+), 5 deletions(-)
diff --git a/Documentation/power/pm_qos_interface.txt
b/Documentation/power/pm_qos_interface.txt
index bfed898..17e130a 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -4,14 +4,19 @@ This interface provides a kernel and user mode interface
for registering
performance expectations by drivers, subsystems and user space applications
on
one of the parameters.
-Currently we have {cpu_dma_latency, network_latency, network_throughput} as
the
-initial set of pm_qos parameters.
+Two different PM QoS frameworks are available:
+1. PM QoS classes for cpu_dma_latency, network_latency, network_throughput.
+2. the per-device PM QoS framework provides the API to manage the per-device
latency
+constraints.
Each parameters have defined units:
* latency: usec
* timeout: usec
* throughput: kbs (kilo bit / sec)
+
+1. PM QoS framework
+
The infrastructure exposes multiple misc device nodes one per implemented
parameter. The set of parameters implement is defined by pm_qos_power_init()
and pm_qos_params.h. This is done because having the available parameters
@@ -23,14 +28,18 @@ an aggregated target value. The aggregated target value
is updated with
changes to the request list or elements of the list. Typically the
aggregated target value is simply the max or min of the request values held
in the parameter list elements.
+Note: the aggregated target value is implemented as an atomic variable so
that
+reading the aggregated value does not require any locking mechanism.
+
From kernel mode the use of this interface is simple:
-handle = pm_qos_add_request(param_class, target_value):
-Will insert an element into the list for that identified PM_QOS class with
the
+void pm_qos_add_request(handle, param_class, target_value):
+Will insert an element into the list for that identified PM QoS class with
the
target value. Upon change to this list the new target is recomputed and any
registered notifiers are called only if the target value is now different.
-Clients of pm_qos need to save the returned handle.
+Clients of pm_qos need to save the returned handle for future use in other
+pm_qos API functions.
void pm_qos_update_request(handle, new_target_value):
Will update the list element pointed to by the handle with the new target
value
@@ -42,6 +51,20 @@ Will remove the element. After removal it will update the
aggregate target and
call the notification tree if the target was changed as a result of removing
the request.
+int pm_qos_request(param_class):
+Returns the aggregated value for a given PM QoS class.
+
+int pm_qos_request_active(handle):
+Returns if the request is still active, i.e. it has not been removed from a
+PM QoS class constraints list.
+
+int pm_qos_add_notifier(param_class, notifier):
+Adds a notification callback function to the PM QoS class. The callback is
+called when the aggregated value for the PM QoS class is changed.
+
+int pm_qos_remove_notifier(int param_class, notifier):
+Removes the notification callback function for the PM QoS class.
+
From user mode:
Only processes can register a pm_qos request. To provide for automatic
@@ -63,4 +86,63 @@ To remove the user mode request for a target value simply
close the device
node.
+2. PM QoS per-device latency framework
+
+For each device a list of performance requests is maintained along with
+an aggregated target value. The aggregated target value is updated with
+changes to the request list or elements of the list. Typically the
+aggregated target value is simply the max or min of the request values held
+in the parameter list elements.
+Note: the aggregated target value is implemented as an atomic variable so
that
+reading the aggregated value does not require any locking mechanism.
+
+
+From kernel mode the use of this interface is the following:
+
+int dev_pm_qos_add_request(device, handle, value):
+Will insert an element into the list for that identified device with the
+target value. Upon change to this list the new target is recomputed and any
+registered notifiers are called only if the target value is now different.
+Clients of dev_pm_qos need to save the handle for future use in other
+dev_pm_qos API functions.
+
+int dev_pm_qos_update_request(handle, new_value):
+Will update the list element pointed to by the
[PATCH] PM QoS: update Documentation for the pm_qos and dev_pm_qos frameworks
From: Jean Pihet j-pi...@ti.com
Update the documentation for the recently updated pm_qos API, kernel
and user space.
Add the documentation for the per-device PM QoS (dev_pm_qos) framework
API.
Signed-off-by: Jean Pihet j-pi...@ti.com
---
Documentation/power/pm_qos_interface.txt | 92 --
1 files changed, 87 insertions(+), 5 deletions(-)
diff --git a/Documentation/power/pm_qos_interface.txt
b/Documentation/power/pm_qos_interface.txt
index bfed898..17e130a 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -4,14 +4,19 @@ This interface provides a kernel and user mode interface for
registering
performance expectations by drivers, subsystems and user space applications on
one of the parameters.
-Currently we have {cpu_dma_latency, network_latency, network_throughput} as the
-initial set of pm_qos parameters.
+Two different PM QoS frameworks are available:
+1. PM QoS classes for cpu_dma_latency, network_latency, network_throughput.
+2. the per-device PM QoS framework provides the API to manage the per-device
latency
+constraints.
Each parameters have defined units:
* latency: usec
* timeout: usec
* throughput: kbs (kilo bit / sec)
+
+1. PM QoS framework
+
The infrastructure exposes multiple misc device nodes one per implemented
parameter. The set of parameters implement is defined by pm_qos_power_init()
and pm_qos_params.h. This is done because having the available parameters
@@ -23,14 +28,18 @@ an aggregated target value. The aggregated target value is
updated with
changes to the request list or elements of the list. Typically the
aggregated target value is simply the max or min of the request values held
in the parameter list elements.
+Note: the aggregated target value is implemented as an atomic variable so that
+reading the aggregated value does not require any locking mechanism.
+
From kernel mode the use of this interface is simple:
-handle = pm_qos_add_request(param_class, target_value):
-Will insert an element into the list for that identified PM_QOS class with the
+void pm_qos_add_request(handle, param_class, target_value):
+Will insert an element into the list for that identified PM QoS class with the
target value. Upon change to this list the new target is recomputed and any
registered notifiers are called only if the target value is now different.
-Clients of pm_qos need to save the returned handle.
+Clients of pm_qos need to save the returned handle for future use in other
+pm_qos API functions.
void pm_qos_update_request(handle, new_target_value):
Will update the list element pointed to by the handle with the new target value
@@ -42,6 +51,20 @@ Will remove the element. After removal it will update the
aggregate target and
call the notification tree if the target was changed as a result of removing
the request.
+int pm_qos_request(param_class):
+Returns the aggregated value for a given PM QoS class.
+
+int pm_qos_request_active(handle):
+Returns if the request is still active, i.e. it has not been removed from a
+PM QoS class constraints list.
+
+int pm_qos_add_notifier(param_class, notifier):
+Adds a notification callback function to the PM QoS class. The callback is
+called when the aggregated value for the PM QoS class is changed.
+
+int pm_qos_remove_notifier(int param_class, notifier):
+Removes the notification callback function for the PM QoS class.
+
From user mode:
Only processes can register a pm_qos request. To provide for automatic
@@ -63,4 +86,63 @@ To remove the user mode request for a target value simply
close the device
node.
+2. PM QoS per-device latency framework
+
+For each device a list of performance requests is maintained along with
+an aggregated target value. The aggregated target value is updated with
+changes to the request list or elements of the list. Typically the
+aggregated target value is simply the max or min of the request values held
+in the parameter list elements.
+Note: the aggregated target value is implemented as an atomic variable so that
+reading the aggregated value does not require any locking mechanism.
+
+
+From kernel mode the use of this interface is the following:
+
+int dev_pm_qos_add_request(device, handle, value):
+Will insert an element into the list for that identified device with the
+target value. Upon change to this list the new target is recomputed and any
+registered notifiers are called only if the target value is now different.
+Clients of dev_pm_qos need to save the handle for future use in other
+dev_pm_qos API functions.
+
+int dev_pm_qos_update_request(handle, new_value):
+Will update the list element pointed to by the handle with the new target value
+and recompute the new aggregated target, calling the notification trees if the
+target is changed.
+
+int dev_pm_qos_remove_request(handle):
+Will remove the element. After removal it will update the aggregate target and
+call the
