From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262580AbUAOVNA (ORCPT ); Thu, 15 Jan 2004 16:13:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261812AbUAOVKb (ORCPT ); Thu, 15 Jan 2004 16:10:31 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:37099 "EHLO atrey.karlin.mff.cuni.cz") by vger.kernel.org with ESMTP id S263734AbUAOVIB (ORCPT ); Thu, 15 Jan 2004 16:08:01 -0500 Date: Thu, 15 Jan 2004 21:48:48 +0100 From: Pavel Machek To: Dave Jones , Linux Kernel Mailing List Subject: Re: BIOS Flash changes PowerNOW frequencies? Message-ID: <20040115204847.GH467@openzaurus.ucw.cz> References: <20040111175610.GA26855@dotnetslash.net> <20040114050818.GC23845@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040114050818.GC23845@redhat.com> User-Agent: Mutt/1.3.27i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > is "Why?". If the CPU and chipset support both sets of frequencies with > > different BIOS, wouldn't the _real_ set of supported frequencies be the union > > of the 2? > > In reality, yes. > However BIOS programmers have a different perception of reality to the rest of us. > The spec for PST tables allows for up to 256 FID/VID pairs, yet everyone just > seems to offer 5-6 as maximum. I guess they figured no-one needed the granularity > of the full range. Imagine tests needed to check that hw is stable at each supported frequency. At that point I understand they only support 6 of them... > Something that has been planned for quite a while has been a means of overriding > the tables using sysfs. I haven't had time to implement this, and no-one else > has found the time/motivation to do so either it seems. > That would be nice. Both notebooks that I have do have broken PST's... Ouch. > Something I was tempted to do at one point (due to the number of broken PST's out > there) was to offer a 'ignore_pst' module parameter, which exposed the full table > to sysfs. The only problem being some VRMs can't handle certain frequencies at > certain voltages whilst some can, making it hard to find a set of 'safe' values > for each frequency. > > How to find out which one VRM can handle frequency X at voltage Y ? > Through the PST tables. Well, you can try it, if it dies, remembed "bad combination" else compile kernel, if it works, it probably is usable combination... at least thats how I did it by hand on k7 notebook. Pavel -- 64 bytes from 195.113.31.123: icmp_seq=28 ttl=51 time=448769.1 ms