Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757583AbZJaJpG (ORCPT ); Sat, 31 Oct 2009 05:45:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757498AbZJaJpD (ORCPT ); Sat, 31 Oct 2009 05:45:03 -0400 Received: from smtp.wp.pl ([212.77.101.1]:42044 "EHLO mx1.wp.pl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757377AbZJaJpB (ORCPT ); Sat, 31 Oct 2009 05:45:01 -0400 Date: Sat, 31 Oct 2009 11:03:01 +0100 From: Krzysztof Helt To: Dave Jones Cc: cpufreq@vger.kernel.org, LKLM , Ingo Molnar Subject: [PATCH] powernow-k6: set transition latency value so ondemand governor can be used Message-Id: <20091031110301.eb3c83d3.krzysztof.h1@wp.pl> In-Reply-To: <20091025032813.GB2475@redhat.com> References: <20091024172538.e2c8776b.krzysztof.h1@poczta.fm> <20091025032813.GB2475@redhat.com> X-Mailer: Sylpheed 2.4.3 (GTK+ 2.11.0; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-WP-AV: skaner antywirusowy poczty Wirtualnej Polski S. A. X-WP-SPAM: NO 0000000 [0dME] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1926 Lines: 49 From: Krzysztof Helt Set the transition latency to value smaller than CPUFREQ_ETERNAL so governors other than "performance" work (like the "ondemand" one). The value is found in "AMD PowerNow! Technology Platform Design Guide for Embedded Processors" dated December 2000 (AMD doc #24267A). There is the answer to one of FAQs on page 40 which states that suggested complete transition period is 200 us. Tested on K6-2+ CPU with K6-3 core (model 13, stepping 4). Signed-off-by: Krzysztof Helt --- This is the second version of the patch with added comment into the source code. arch/x86/kernel/cpu/cpufreq/powernow-k6.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k6.c b/arch/x86/kernel/cpu/cpufreq/powernow-k6.c index f10dea4..15f84a6 100644 --- a/arch/x86/kernel/cpu/cpufreq/powernow-k6.c +++ b/arch/x86/kernel/cpu/cpufreq/powernow-k6.c @@ -163,8 +163,15 @@ static int powernow_k6_cpu_init(struct cpufreq_policy *policy) clock_ratio[i].frequency = busfreq * f; } - /* cpuinfo and default policy values */ - policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; + /* + * cpuinfo and default policy values + * + * The value is found in "AMD PowerNow! Technology Platform + * Design Guide for Embedded Processors" dated December 2000 + * (AMD doc #24267A). There is the answer to one of FAQs on page 40 + * which states that suggested complete transition period is 200 us. + */ + policy->cpuinfo.transition_latency = 200000; policy->cur = busfreq * max_multiplier; result = cpufreq_frequency_table_cpuinfo(policy, clock_ratio); -- 1.6.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/