From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: Re: speedstep-smi woes Date: Tue, 18 Nov 2003 21:34:55 +0100 Sender: cpufreq-bounces@www.linux.org.uk Message-ID: <20031118203455.GA7896@brodo.de> References: <20031118182046.GA5950@brodo.de> <20031118190934.GD32464@poupinou.org> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20031118190934.GD32464@poupinou.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: cpufreq-bounces@www.linux.org.uk Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ducrot Bruno Cc: cpufreq@www.linux.org.uk On Tue, Nov 18, 2003 at 08:09:34PM +0100, Ducrot Bruno wrote: > On Tue, Nov 18, 2003 at 07:20:46PM +0100, Dominik Brodowski wrote: > > Under heavy load speedstep-smi generates "cpufreq: change failed" messages > > at least on two systems, one of them my own. I've tried to evaluate how to > > avoid these failures: > > > > - wbinvd() has no positive effect > > - disabling bus master arbitration (io-port 0x22 on 440bx) has no positive effect > > - mdelay(250) immediately before the asm smi call has resulted in _zero_ > > failures. > > > > However, in most cases, even under heavy load, the speedstep-smi driver > > _does_ achieve speedstep transitions. > > > > So, how to proceed? > > a) Try to avoid these failures, even if the cost of all transitions is 250ms > > then? This practically disables dynamic frequency scaling for > > speedstep-smi. > > b) Do the same as before: this means that sometimes the frequency isn't > > changed even though the user or the dynamic frequency scaling governor > > demands a higher frequency. Also, the "speedstep_init" step tends to fail > > sometimes. > > > > Have you done testing with ide stuff in pio mode? No, as I don't want to lose UDMA2. However, it seems to work. Why? Also, how do we disable DMA safely during a call to speedstep_smi_set_freq()? kernel/dma.c and include/asm/dma.h neither show a way to "disable" DMA like it can be done for preempt, irqs, etc. I really don't want to tell users: disable DMA if you want to use this speedstep driver... Dominik