linux-kernel - [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation

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Message-id: <1372927830-2949-8-git-send-email-l.majewski@samsung.com>
Date:	Thu, 04 Jul 2013 10:50:30 +0200
From:	Lukasz Majewski <l.majewski@...sung.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <eduardo.valentin@...com>
Cc:	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	Lukasz Majewski <l.majewski@...sung.com>, l.majewski@...ess.pl,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andre Przywara <andre.przywara@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>
Subject: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation

Since the support for software and hardware controlled boosting has been
added, the corresponding Documentation entry had been updated.

Signed-off-by: Lukasz Majewski <l.majewski@...sung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@...sung.com>

---
Changes for v5:
- New patch

 Documentation/cpu-freq/boost.txt |   26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/Documentation/cpu-freq/boost.txt b/Documentation/cpu-freq/boost.txt
index 9b4edfc..dd62e13 100644
--- a/Documentation/cpu-freq/boost.txt
+++ b/Documentation/cpu-freq/boost.txt
@@ -17,8 +17,8 @@ Introduction
 Some CPUs support a functionality to raise the operating frequency of
 some cores in a multi-core package if certain conditions apply, mostly
 if the whole chip is not fully utilized and below it's intended thermal
-budget. This is done without operating system control by a combination
-of hardware and firmware.
+budget. The decision about boost disable/enable is made either at hardware
+(e.g. x86) or software (e.g ARM).
 On Intel CPUs this is called "Turbo Boost", AMD calls it "Turbo-Core",
 in technical documentation "Core performance boost". In Linux we use
 the term "boost" for convenience.
@@ -48,24 +48,24 @@ be desirable:
 User controlled switch
 ----------------------
 
-To allow the user to toggle the boosting functionality, the acpi-cpufreq
-driver exports a sysfs knob to disable it. There is a file:
+To allow the user to toggle the boosting functionality, the cpufreq core
+driver exports a sysfs knob to enable or disable it. There is a file:
 /sys/devices/system/cpu/cpufreq/boost
 which can either read "0" (boosting disabled) or "1" (boosting enabled).
-Reading the file is always supported, even if the processor does not
-support boosting. In this case the file will be read-only and always
-reads as "0". Explicitly changing the permissions and writing to that
-file anyway will return EINVAL.
+The file is exported only when cpufreq driver supports boosting.
+Explicitly changing the permissions and writing to that file anyway will
+return EINVAL.
 
 On supported CPUs one can write either a "0" or a "1" into this file.
 This will either disable the boost functionality on all cores in the
-whole system (0) or will allow the hardware to boost at will (1).
+whole system (0) or will allow the software or hardware to boost at will
+(1).
 
 Writing a "1" does not explicitly boost the system, but just allows the
-CPU (and the firmware) to boost at their discretion. Some implementations
-take external factors like the chip's temperature into account, so
-boosting once does not necessarily mean that it will occur every time
-even using the exact same software setup.
+CPU to boost at their discretion. Some implementations take external
+factors like the chip's temperature into account, so boosting once does
+not necessarily mean that it will occur every time even using the exact
+same software setup.
 
 
 AMD legacy cpb switch
-- 
1.7.10.4

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