Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751191AbZIHQDr (ORCPT ); Tue, 8 Sep 2009 12:03:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750990AbZIHQDq (ORCPT ); Tue, 8 Sep 2009 12:03:46 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:36582 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750870AbZIHQDq (ORCPT ); Tue, 8 Sep 2009 12:03:46 -0400 Date: Tue, 8 Sep 2009 12:03:48 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: linux-ide@vger.kernel.org, Kernel development list Subject: Limiting DMA speeds for individual IDE drives Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 935 Lines: 23 Is there any simple way to force the old IDE driver to limit the DMA speed for a particular device? I've got a situation where a drive claims to be capable of supporting UDMA/100, but it's in a noisy environment and gets lots of errors at that speed. I'd like to limit it to UDMA/66 or even UDMA/33. The hdparm command should be able to do this but I can't run it until the system has booted, by which time a bunch of CRC and possibly other errors have already occurred. Ideally it should be possible to limit the speed starting as early as device detection, but I can't find any way to do it. Is there support for such a thing or will I have to hack it in? Thanks, Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/