From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Frank Subject: Re: Cpufreq: powernow-k7 weirdness Date: Mon, 7 Jul 2003 23:06:10 +0800 Sender: cpufreq-admin@www.linux.org.uk Message-ID: <200307072306.13290.mflt1@micrologica.com.hk> References: <200307071129.46683.mflt1@micrologica.com.hk> <20030707131252.GC7796@poupinou.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20030707131252.GC7796@poupinou.org> Content-Disposition: inline Errors-To: cpufreq-admin@www.linux.org.uk List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: Ducrot Bruno Cc: Luigi Belli , cpufreq@www.linux.org.uk On Monday 07 July 2003 21:12, Ducrot Bruno wrote: > > The actual minimum time between steps depends on systems design and can > > only be established by watching the (core) voltage on an oscilloscope > > while modulating cpufreq/ACPI settings. The time used should be double > > or triple the minimum for longterm stability. It would be better if > > Mainboard manufacturers would specify this minimum time. > > That is suposed to be done via a BIOS table (with signature > AMDK7PNOW!) for the powernow-k7 driver, but is used for the > CPU only (I believe), and I guess that anyway this occur > only when a valid core voltage is applied to the CPU (well, > I hope). > But perhaps this table do not give appropriate values on some system? > > Actually, I was wondering why the _PSS method (from ACPI) give > a settling time of 125us, instead of 100us for some systems. 100us vs 125us won't matter unless the margin is too small already. I don't know anything about the big CPU chip requirements as I have never read a datasheet on on those big beasts. My comments were related to the (analog side of the) power supply limitations. IMHO mainboard Vcore switchers could do a step in 100us or so, or full scale over 10 steps or so, (weaker) main power supplies would likely have trouble as their switching frequency is much lower. Perhaps a mainboard designer could comment? Regards Michael -- Powered by linux-2.5.74-mm1. Compiled with gcc-2.95-3 - mature and rock solid My current linux related activities: - 2.5 yenta_socket testing - Test development and testing of swsusp and ACPI S3 - Everyday usage of 2.5 kernel More info on 2.5 kernel: http://www.codemonkey.org.uk/post-halloween-2.5.txt