From patchwork Sun Jan 5 10:21:14 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ramkumar Ramachandra X-Patchwork-Id: 3434521 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 432599F2E9 for ; Sun, 5 Jan 2014 10:21:18 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4822420163 for ; Sun, 5 Jan 2014 10:21:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D71720145 for ; Sun, 5 Jan 2014 10:21:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751001AbaAEKVP (ORCPT ); Sun, 5 Jan 2014 05:21:15 -0500 Received: from mail-pb0-f52.google.com ([209.85.160.52]:45270 "EHLO mail-pb0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750915AbaAEKVO (ORCPT ); Sun, 5 Jan 2014 05:21:14 -0500 Received: by mail-pb0-f52.google.com with SMTP id uo5so17379118pbc.39 for ; Sun, 05 Jan 2014 02:21:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=6cF5PWBoDJCXyAu48e2/6ypK+sqDQVhu5uosFEa4CPg=; b=M7r9ZHj920Or19ezCul4ptYxZG0VsbungzaOsNOk+EtIqSJD0+BMNZg5ryWkog8fou qtIsltL45sRwz9s40D6bNIfMN+lQrL+pirSY5f+vclHILTyXkC84tp7RGBVCufknoDvZ +HHEhG5BAWuIeFQ0yrFGdCaEFqouC/zfg1orCHM5Yg/3qcoe/UyNx0ytehx2eAylyle3 oMTiUnb/yDDKhjZOC3qKNuiZPEn0pBmh1YoYRpqNxE8WPh/rInh45ZutxgjQGUrQ6se/ CGyjuJTKcK1cj/5MgKQnQYozp6bZp/vpgs0uuUmVbdvyN4Ubg2HYL2TaZ8JFUO3ZWnDS AJRQ== X-Received: by 10.68.218.165 with SMTP id ph5mr113676922pbc.11.1388917273682; Sun, 05 Jan 2014 02:21:13 -0800 (PST) Received: from localhost.localdomain ([122.164.141.93]) by mx.google.com with ESMTPSA id by1sm121031354pbd.25.2014.01.05.02.21.10 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 05 Jan 2014 02:21:12 -0800 (PST) From: Ramkumar Ramachandra To: LKML Cc: Dirk Brandewie , "Rafael J. Wysocki" , Randy Dunlap , Linux PM Subject: [PATCH v3] Documentation/cpu-freq: add intel-pstate.txt Date: Sun, 5 Jan 2014 15:51:14 +0530 Message-Id: <1388917274-19241-1-git-send-email-artagnon@gmail.com> X-Mailer: git-send-email 1.8.5.2.227.g53f3478 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The Intel P-state driver is currently undocumented. Add some documentation based on the cover-letter sent with the original series. Cc: Dirk Brandewie Cc: Rafael J. Wysocki Cc: Randy Dunlap Cc: Linux PM Acked-by: Randy Dunlap Signed-off-by: Ramkumar Ramachandra --- Documentation/cpu-freq/intel-pstate.txt | 40 +++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 Documentation/cpu-freq/intel-pstate.txt diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-freq/intel-pstate.txt new file mode 100644 index 0000000..e742d21 --- /dev/null +++ b/Documentation/cpu-freq/intel-pstate.txt @@ -0,0 +1,40 @@ +Intel P-state driver +-------------------- + +This driver implements a scaling driver with an internal governor for +Intel Core processors. The driver follows the same model as the +Transmeta scaling driver (longrun.c) and implements the setpolicy() +instead of target(). Scaling drivers that implement setpolicy() are +assumed to implement internal governors by the cpufreq core. All the +logic for selecting the current P state is contained within the +driver; no external governor is used by the cpufreq core. + +Intel SandyBridge+ processors are supported. + +New sysfs files for controlling P state selection have been added to +/sys/devices/system/cpu/intel_pstate/ + + max_perf_pct: limits the maximum P state that will be requested by + the driver stated as a percentage of the available performance. + + min_perf_pct: limits the minimum P state that will be requested by + the driver stated as a percentage of the available performance. + + no_turbo: limits the driver to selecting P states below the turbo + frequency range. + +For contemporary Intel processors, the frequency is controlled by the +processor itself and the P-states exposed to software are related to +performance levels. The idea that frequency can be set to a single +frequency is fiction for Intel Core processors. Even if the scaling +driver selects a single P state the actual frequency the processor +will run at is selected by the processor itself. + +New debugfs files have also been added to /sys/kernel/debug/pstate_snb/ + + deadband + d_gain_pct + i_gain_pct + p_gain_pct + sample_rate_ms + setpoint