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PM: QoS: Update file information comments

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Update the file information comments in include/linux/pm_qos.h
and kernel/power/qos.c by adding titles along with copyright and
authors information to them and changing the qos.c description to
better reflect its contents (outdated information is dropped from
it in particular).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Tested-by: Amit Kucheria <amit.kucheria@linaro.org>
This commit is contained in:
Rafael J. Wysocki 2020-02-12 00:35:39 +01:00
parent 67b06ba018
commit fe52de36dc
2 changed files with 23 additions and 26 deletions
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15
include/linux/pm_qos.h
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@ -1,10 +1,17 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Definitions related to Power Management Quality of Service (PM QoS).
*
* Copyright (C) 2020 Intel Corporation
*
* Authors:
* Mark Gross <mgross@linux.intel.com>
* Rafael J. Wysocki <rafael.j.wysocki@intel.com>
*/
#ifndef _LINUX_PM_QOS_H
#define _LINUX_PM_QOS_H
/* interface for the pm_qos_power infrastructure of the linux kernel.
*
* Mark Gross <mgross@linux.intel.com>
*/
#include <linux/plist.h>
#include <linux/notifier.h>
#include <linux/device.h>

34
kernel/power/qos.c
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@ -1,31 +1,21 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* This module exposes the interface to kernel space for specifying
* QoS dependencies. It provides infrastructure for registration of:
* Power Management Quality of Service (PM QoS) support base.
*
* Dependents on a QoS value : register requests
* Watchers of QoS value : get notified when target QoS value changes
* Copyright (C) 2020 Intel Corporation
*
* This QoS design is best effort based. Dependents register their QoS needs.
* Watchers register to keep track of the current QoS needs of the system.
* Authors:
* Mark Gross <mgross@linux.intel.com>
* Rafael J. Wysocki <rafael.j.wysocki@intel.com>
*
* There are 3 basic classes of QoS parameter: latency, timeout, throughput
* each have defined units:
* latency: usec
* timeout: usec <-- currently not used.
* throughput: kbs (kilo byte / sec)
* Provided here is an interface for specifying PM QoS dependencies. It allows
* entities depending on QoS constraints to register their requests which are
* aggregated as appropriate to produce effective constraints (target values)
* that can be monitored by entities needing to respect them, either by polling
* or through a built-in notification mechanism.
*
* There are lists of pm_qos_objects each one wrapping requests, notifiers
*
* User mode requests on a QOS parameter register themselves to the
* subsystem by opening the device node /dev/... and writing there request to
* the node. As long as the process holds a file handle open to the node the
* client continues to be accounted for. Upon file release the usermode
* request is removed and a new qos target is computed. This way when the
* request that the application has is cleaned up when closes the file
* pointer or exits the pm_qos_object will get an opportunity to clean up.
*
* Mark Gross <mgross@linux.intel.com>
* In addition to the basic functionality, more specific interfaces for managing
* global CPU latency QoS requests and frequency QoS requests are provided.
*/
/*#define DEBUG*/