From owner-freebsd-hardware@FreeBSD.ORG Thu Jul 7 04:37:04 2011 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7C9D7106566C for ; Thu, 7 Jul 2011 04:37:04 +0000 (UTC) (envelope-from perryh@pluto.rain.com) Received: from agora.rdrop.com (agora.rdrop.com [IPv6:2607:f678:1010::34]) by mx1.freebsd.org (Postfix) with ESMTP id 010A38FC0C for ; Thu, 7 Jul 2011 04:37:03 +0000 (UTC) Received: from agora.rdrop.com (66@localhost [127.0.0.1]) by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id p674b2Yi059528 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Wed, 6 Jul 2011 21:37:02 -0700 (PDT) (envelope-from perryh@pluto.rain.com) Received: (from uucp@localhost) by agora.rdrop.com (8.13.1/8.12.9/Submit) with UUCP id p674b1Yl059526 for freebsd-hardware@freebsd.org; Wed, 6 Jul 2011 21:37:01 -0700 (PDT) Received: from fbsd61 by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407) id AA22753; Wed, 6 Jul 11 21:35:29 PDT Date: Wed, 06 Jul 2011 21:35:22 -0700 From: perryh@pluto.rain.com To: freebsd-hardware@freebsd.org Message-Id: <4e15378a.FzdckfPKoy0B4rU6%perryh@pluto.rain.com> References: <4e082cfb.RsTdPgXYWUCS9sX7%perryh@pluto.rain.com> In-Reply-To: <4e082cfb.RsTdPgXYWUCS9sX7%perryh@pluto.rain.com> User-Agent: nail 11.25 7/29/05 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: VIA VT6421 w/a (Re: UDMA cables vs speeds) X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 Jul 2011 04:37:04 -0000 This is for the archives. The original posting is here: http://lists.freebsd.org/pipermail/freebsd-hardware/2011-June/006704.html > Should an 80-wire Ultra-ATA data cable intended for use at UDMA66 > or UDMA100 also work at UDMA133, or does the higher speed require > different cabling? Answer: as nearly as I've been able to determine, there are only two kinds of PATA data cables: the original 40-wire variety that work for PIO and for UDMA33, and the newer 80-wire variety that should work for all modes. > ... I've been experiencing occasional UDMA ICRC errors on the > IDE port of a PCI SATA/IDE controller card using the VIA VT6421 > chipset, and I've noticed that "atacontrol mode" reports the > port speed as UDMA133. The data cable is brand new ... > I've found several similar reports in the forum and mailing-list > archives, with no definitive solution but quite a few "it works > for me" responses, and one observation that the VT6421 seems to > work well with some drives and not so well with others. It occurs > to me that the difference might, perhaps, involve the DMA speeds DMA speed definitely seems to be a factor. The errors seem to have been completely eliminated after I used atacontrol mode ad8 UDMA100 to limit the maximum transfer rate. Throttling the DMA speed is not an ideal solution, and I still have no clue _why_ it doesn't work reliably at UDMA133, but this does seem to have gotten around the problem.