From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422835Ab3LTOZm (ORCPT ); Fri, 20 Dec 2013 09:25:42 -0500 Received: from mailout1.samsung.com ([203.254.224.24]:32738 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422815Ab3LTOZi (ORCPT ); Fri, 20 Dec 2013 09:25:38 -0500 X-AuditID: cbfee61b-b7f456d000006dfd-f1-52b453614e53 From: Lukasz Majewski To: Viresh Kumar , "Rafael J. Wysocki" , Eduardo Valentin Cc: "cpufreq@vger.kernel.org" , Linux PM list , Jonghwa Lee , Lukasz Majewski , Lukasz Majewski , linux-kernel , Bartlomiej Zolnierkiewicz , Myungjoo Ham , durgadoss.r@intel.com, Zhang Rui , linux-samsung-soc@vger.kernel.org Subject: [PATCH v12 5/7] Documentation:cpufreq:boost: Update BOOST documentation Date: Fri, 20 Dec 2013 15:24:53 +0100 Message-id: <1387549495-809-6-git-send-email-l.majewski@samsung.com> X-Mailer: git-send-email 1.7.10.4 In-reply-to: <1387549495-809-1-git-send-email-l.majewski@samsung.com> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1387549495-809-1-git-send-email-l.majewski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrHLMWRmVeSWpSXmKPExsVy+t9jQd3E4C1BBo9faVlsnLGe1eJp0w92 i76fV5gt1uz/yWTRefYJs8WbR9wWbx5uZrS4vGsOm8Xn3iOMFjPO72OyuN24gs3izOlLrBZP HvaxWWz86uHA57F4z0smjzvX9rB5rJv2ltljy9V2Fo++LasYPY7f2M7k8XmTXAB7FJdNSmpO Zllqkb5dAldG54Tl7AUfJCvu33jG0sDYL9rFyMEhIWAi8e+zdxcjJ5ApJnHh3nq2LkYuDiGB 6YwSqzo3MEI4XUwSP6YtYQKpYhPQk/h89ymYLSLQzChx67kfSBGzwCVmiY6lV5lBEsICARKP f29jAtnAIqAqcW5xPEiYV8BFYtKGHnaIbYoS3c8msIHYnAKuEqvX3mEEsYUEGhglmjaqTmDk XcDIsIpRNLUguaA4KT3XSK84Mbe4NC9dLzk/dxMjOFSfSe9gXNVgcYhRgINRiYe3QH9zkBBr YllxZe4hRgkOZiUR3s8+W4KEeFMSK6tSi/Lji0pzUosPMUpzsCiJ8x5stQ4UEkhPLEnNTk0t SC2CyTJxcEo1MK4UleYMXR3JELXz1nqGrC+TG/gq76x5oW60sbctYur8To2QtR8mzKprClsk fbrVZ4FK9WdzhQjOv5zNTlMXrZwexiOSG7uvxJ3pR++2lTrKs/dtfsG68o7ATI/F4k2ieku+ rz9x4FS9ycmtLnwRlgsqQ7aWqfSu9N9bI2Sd13XMwieM4c3KCCWW4oxEQy3mouJEAOwQ99VR AgAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since the support for software and hardware controlled boosting has been added, the corresponding Documentation entry had been updated. Signed-off-by: Lukasz Majewski Signed-off-by: Myungjoo Ham Acked-by: Viresh Kumar --- Changes for v12: - None Changes for v11: - None Changes for v10: - None Changes for v9: - None Changes for v8: - None Changes for v7: - None Changes for v6: - None 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