Messages in this thread Patch in this message | | | Date | Tue, 26 Feb 2013 10:10:49 -0600 | From | Nishanth Menon <> | Subject | Re: [GIT PULL] ACPI and power management fixes for v3.9-rc1 |
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On 16:55-20130226, Rafael J. Wysocki wrote: > On Monday, February 25, 2013 09:31:45 PM Linus Torvalds wrote: > > On Mon, Feb 25, 2013 at 7:17 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote: [..] > > > This has become a huge problem, to the point that we have a > > "Documentation/power/opp.txt" file THAT NEVER CLEARLY STATES WHAT THE > > F*CK OPP ACTUALLY MEANS! What nice "documentation". > > It says that in "Introduction", but it would be clearer if the title of the > doc was something like "Operating Performance Points (OPP) Library". Nishanth? Yes indeed. Will the following help? I can post it as an official patch if the direction is proper. diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt index 3035d00..4a17443 100644 --- a/Documentation/power/opp.txt +++ b/Documentation/power/opp.txt @@ -1,5 +1,5 @@ *=============* -* OPP Library * +* Operating Performance Points (OPP) Library * *=============* (C) 2009-2010 Nishanth Menon <nm@ti.com>, Texas Instruments Incorporated @@ -16,6 +16,8 @@ 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 @@ -25,6 +27,16 @@ more. 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: +MPU device supports {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 +{300000, 1000000} +{800000, 1200000} +{1000000, 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 -- Regards, Nishanth Menon
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