On 02/26/13 15:53, Nishanth Menon wrote: > Make Operating Performance Points (OPP) library introductory chapter > a little more reader-friendly. Split the chapter into two sections, > highlight the definition with an example and minor rewording to be > verbose. > > Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Cc: "Rafael J. Wysocki" <rjw@xxxxxxx> > Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > Cc: linux-pm@xxxxxxxxxxxxxxx > Cc: linux-doc@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Signed-off-by: Nishanth Menon <nm@xxxxxx> Reviewed-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Thanks. > --- > v2: > review updates from v1 > > v1: https://patchwork.kernel.org/patch/2186921/ > originally reported in thread http://marc.info/?t=135760248900003&r=1&w=2 > > Documentation/power/opp.txt | 25 ++++++++++++++++++++----- > 1 file 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@xxxxxx>, 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 > -- ~Randy -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
