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author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-03-06 23:42:05 +0100 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-03-06 23:42:05 +0100 |
commit | 6bd51658fae374557b063155bd4465411acd12fc (patch) | |
tree | c3f4a8e6b350ec1f3aef77502714ac8e1f898e4e /Documentation | |
parent | d7553a86b5cd18d46ad3eabebadedcb45eda3ab1 (diff) | |
parent | d3929b832833db870af72479666fa4e4d043e02e (diff) | |
download | op-kernel-dev-6bd51658fae374557b063155bd4465411acd12fc.zip op-kernel-dev-6bd51658fae374557b063155bd4465411acd12fc.tar.gz |
Merge branch 'pm-fixes' into fixes
* pm-fixes:
cpufreq / intel_pstate: Do not load on VM that does not report max P state.
cpufreq / intel_pstate: Fix intel_pstate_init() error path
PM / QoS: Remove device PM QoS sysfs attributes at the right place
PM / QoS: Fix concurrency issues and memory leaks in device PM QoS
cpufreq: highbank: do not initialize array with a loop
PM / OPP: improve introductory documentation
cpufreq: Fix a typo in comment
mailbox, pl320-ipc: remove __init from probe function
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/power/opp.txt | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt index 3035d00..425c51d 100644 --- a/Documentation/power/opp.txt +++ b/Documentation/power/opp.txt @@ -1,6 +1,5 @@ -*=============* -* OPP Library * -*=============* +Operating Performance Points (OPP) Library +========================================== (C) 2009-2010 Nishanth Menon <nm@ti.com>, Texas Instruments Incorporated @@ -16,15 +15,31 @@ Contents 1. Introduction =============== +1.1 What is an Operating Performance Point (OPP)? + Complex SoCs of today consists of a multiple sub-modules working in conjunction. In an operational system executing varied use cases, not all modules in the SoC need to function at their highest performing frequency all the time. To facilitate this, sub-modules in a SoC are grouped into domains, allowing some -domains to run at lower voltage and frequency while other domains are loaded -more. The set of discrete tuples consisting of frequency and voltage pairs that +domains to run at lower voltage and frequency while other domains run at +voltage/frequency pairs that are higher. + +The set of discrete tuples consisting of frequency and voltage pairs that the device will support per domain are called Operating Performance Points or OPPs. +As an example: +Let us consider an MPU device which supports the following: +{300MHz at minimum voltage of 1V}, {800MHz at minimum voltage of 1.2V}, +{1GHz at minimum voltage of 1.3V} + +We can represent these as three OPPs as the following {Hz, uV} tuples: +{300000000, 1000000} +{800000000, 1200000} +{1000000000, 1300000} + +1.2 Operating Performance Points Library + OPP library provides a set of helper functions to organize and query the OPP information. The library is located in drivers/base/power/opp.c and the header is located in include/linux/opp.h. OPP library can be enabled by enabling |