linux-kernel - Re: [PATCH V2] PM / OPP: improve introductory documentation

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Date:	Tue, 26 Feb 2013 16:45:05 -0800
From:	Randy Dunlap <rdunlap@...radead.org>
To:	Nishanth Menon <nm@...com>
CC:	linux-pm <linux-pm@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] PM / OPP: improve introductory documentation

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@...ux-foundation.org>
> Cc: "Rafael J. Wysocki" <rjw@...k.pl>
> Cc: Randy Dunlap <rdunlap@...radead.org>
> Cc: linux-pm@...r.kernel.org
> Cc: linux-doc@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Nishanth Menon <nm@...com>

Reviewed-by: Randy Dunlap <rdunlap@...radead.org>

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@...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
> 


-- 
~Randy
--
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