From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 21 Jan 2001 15:50:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 21 Jan 2001 15:49:56 -0500 Received: from adsl-63-195-162-81.dsl.snfc21.pacbell.net ([63.195.162.81]:54532 "EHLO master.linux-ide.org") by vger.kernel.org with ESMTP id ; Sun, 21 Jan 2001 15:49:47 -0500 Date: Sun, 21 Jan 2001 12:49:40 -0800 (PST) From: Andre Hedrick To: Vojtech Pavlik cc: Mike Galbraith , linux-kernel@vger.kernel.org Subject: Re: [preview] Latest AMD & VIA IDE drivers with UDMA100 support In-Reply-To: <20010121173251.B1073@suse.cz> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 21 Jan 2001, Vojtech Pavlik wrote: > On Sun, Jan 21, 2001 at 01:42:41PM +0100, Mike Galbraith wrote: > > On Sun, 21 Jan 2001, Vojtech Pavlik wrote: > > > > > On Sat, Jan 20, 2001 at 02:57:07PM -0800, Andre Hedrick wrote: > > > > > > > chipset ---\ > > > > | > > > > \---------IDC-header > > > > > > > > chipset ---+ > > > > | > > > > +----------IDC-header > > > > > > > > These are nearly the same but the corners cause bounce and iCRC's > > > > I don't see how anyone can influence risetime falltime or impedance > > matching [1] issues via software timing changes. > > > > (the top drawing is what you see on a poorly designed board.. long > > rise/fall times often cause worse problems than [slight] ringing) > > > > > Well, there are other ways the motherboard maker can screw up the > > > traces, and often this happens: > > > > > > chipset --------\ > > > | > > > chipset ------\ | > > > | \------ header > > > \-------- header > > > > > > > Can you compensate for these things (to any degree?) in software? > > Not really. Slowing the data rate down is in my opinion the only way to > compensate for this. Btw, the chipset only controls the write data rate > with UDMA. The read rate is controlled by the drive. > > > 1. Only a software guy would call it 'bounce'.. sounds funny ;-) Er...I help design some of the hardware and the rules, so I do more than just software. So does 'echo' or 'reflections'sound better than 'bounce'? Cheers, Andre Hedrick Linux ATA Development - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/