From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936649AbXLRALG (ORCPT ); Mon, 17 Dec 2007 19:11:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755440AbXLRAKy (ORCPT ); Mon, 17 Dec 2007 19:10:54 -0500 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:47936 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1756589AbXLRAKy (ORCPT ); Mon, 17 Dec 2007 19:10:54 -0500 Date: Tue, 18 Dec 2007 00:04:05 +0000 From: Alan Cox To: lsorense@csclub.uwaterloo.ca (Lennart Sorensen) Cc: Oliver Joa , linux-kernel@vger.kernel.org Subject: Re: How to Switch DMA off for only one Harddisk at Kernelboot Message-ID: <20071218000405.19d2c706@the-village.bc.nu> In-Reply-To: <20071217223225.GF2310@csclub.uwaterloo.ca> References: <4765690C.6010605@j-o-a.de> <20071217223225.GF2310@csclub.uwaterloo.ca> X-Mailer: Claws Mail 2.10.0 (GTK+ 2.10.14; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Isn't it more a matter of having a CF card that does do DMA and a > controller that does DMA, but a CF to IDE adapter that does not do DMA? Usually yes. If your CF card doesn't support DMA it will advertise PIO modes only and all will be well. If your card can do DMA it will advertise DMA modes regardless of whether your CF adapter has the needed pins wired. For UDMA it is even worse. Most CF adapters that can do DMA do not provide sufficient signal quality for UDMA. In addition if you hang them off a normal UDMA 2 device cable you are miles out of spec and some cards work some of the time. Alan