From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752263Ab1GXDPK (ORCPT ); Sat, 23 Jul 2011 23:15:10 -0400 Received: from DMZ-MAILSEC-SCANNER-1.MIT.EDU ([18.9.25.12]:45742 "EHLO dmz-mailsec-scanner-1.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751160Ab1GXDPG (ORCPT ); Sat, 23 Jul 2011 23:15:06 -0400 X-AuditID: 1209190c-b7bdeae000000a26-14-4e2b8dd10c25 Message-ID: <4E2B8E36.6030308@mit.edu> Date: Sat, 23 Jul 2011 23:15:02 -0400 From: Andy Lutomirski User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20110707 Thunderbird/5.0 MIME-Version: 1.0 To: Matthew Garrett CC: cpufreq@vger.kernel.org, davej@redhat.com, linux-kernel@vger.kernel.org, borislav.petkov@amd.com, mark.langsdorf@amd.com, andreas.herrmann3@amd.com Subject: Re: [PATCH v4 3/7] acpi-cpufreq: Add support for disabling dynamic overclocking References: <1311007062-2050-1-git-send-email-mjg@redhat.com> <1311007062-2050-4-git-send-email-mjg@redhat.com> In-Reply-To: <1311007062-2050-4-git-send-email-mjg@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprMKsWRmVeSWpSXmKPExsUixCmqrXuxV9vP4NlfA4tjy/azWVxdLGvx tOkHu8WW601MFpd3zWGz6Hl6nNViR+92Jgd2j9ZLf9k83u+7yubxeZNcAHMUl01Kak5mWWqR vl0CV8bumcdYCs5zVTx+18ncwHiRo4uRk0NCwETi44xPbBC2mMSFe+uBbC4OIYF9jBJNz16x QzgbGCWWrf7MBOG8ZZKYcm4vK0gLr4CaxIxnx9hBbBYBVYmTf7aA2WwCKhIdSx8wgdiiAkES 9383sEDUC0qcnPkEzBYBqum838UCMpRZYCWjxMK/3cwgCWGBKIkt5yaAFQkJ5Evcv7iRsYuR g4NTwE7iypYcEJNZwFri2+4ikApmAXmJ7W/nME9gFJyFZMMshKpZSKoWMDKvYpRNya3SzU3M zClOTdYtTk7My0st0jXUy80s0UtNKd3ECA57SZ4djG8OKh1iFOBgVOLh3fhFy0+INbGsuDL3 EKMkB5OSKO+nHm0/Ib6k/JTKjMTijPii0pzU4kOMEhzMSiK8l7cAlfOmJFZWpRblw6SkOViU xHnLvf/7CgmkJ5akZqemFqQWwWRlODiUJHjXA+NbSLAoNT21Ii0zpwQhzcTBCTKcB2j4KpAa 3uKCxNzizHSI/ClGRSlx3l0gCQGQREZpHlwvLC29YhQHekWYNxukigeY0uC6XwENZgIaLK+g CTK4JBEhJdXAKPryd4DOIXuzp/GVzWuK2KM6L3xearLx04elcz/9n6t5T8rg1rzpCrNTNIqM hSxPLfq8xXV98B/G2UW1H2bfOcDNue/mlJVirQvEfHK1d975uyFia7rnK+2bC2psuNicprya 5MWY5B17ozeYW9yymqvASX159dXk5q8fHtZIp4iEsEj4/j/nosRSnJFoqMVcVJwIAB9XYugm AwAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/18/2011 12:37 PM, Matthew Garrett wrote: > One feature present in powernow-k8 that isn't present in acpi-cpufreq is > support for enabling or disabling AMD's core performance boost technology. > This patch adds that support to acpi-cpufreq, but also extends it to allow > Intel's dynamic acceleration to be disabled via the same interface. The > sysfs entry retains the cpb name for compatibility purposes. > > Signed-off-by: Matthew Garrett > --- > drivers/cpufreq/acpi-cpufreq.c | 191 ++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 191 insertions(+), 0 deletions(-) > > + if (enable) > + reg->q&= ~MSR_IA32_MISC_ENABLE_TURBO_DISABLE; > + else > + reg->q |= MSR_IA32_MISC_ENABLE_TURBO_DISABLE; > + } I was curious and looked it up. Intel SDM volume 3, 14.3.2.1 says: Opportunistic processor performance operation can be disabled by setting bit 38 of IA32_MISC_ENABLE. This mechanism is intended for BIOS only. If IA32_MISC_ENABLE[38] is set, CPUID.06H:EAX[1] will return 0. and the next section says: System software can temporarily disengage opportunistic processor performance operation by setting bit 32 of the IA32_PERF_CTL MSR (0199H), using a read- modify-write sequence on the MSR. Would that be a better way to control boost mode on Intel chips? --Andy