Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757477AbYFWNGl (ORCPT ); Mon, 23 Jun 2008 09:06:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754213AbYFWNGc (ORCPT ); Mon, 23 Jun 2008 09:06:32 -0400 Received: from hera.kernel.org ([140.211.167.34]:59512 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753965AbYFWNGb (ORCPT ); Mon, 23 Jun 2008 09:06:31 -0400 Message-ID: <485F9FA4.3050608@kernel.org> Date: Mon, 23 Jun 2008 22:05:40 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.12 (X11/20071114) MIME-Version: 1.0 To: Alan Cox CC: benh@kernel.crashing.org, Pavel Machek , Andreas Schwab , kernel list , jgarzik@pobox.com, IDE/ATA development list , Trivial patch monkey Subject: Re: sata_svw data corruption, strange problems References: <20080617093602.GA28140@elf.ucw.cz> <485EF061.3010601@kernel.org> <20080623082055.GB1850@elf.ucw.cz> <20080623085338.GE1850@elf.ucw.cz> <485F6540.6000907@kernel.org> <20080623090130.GF1850@elf.ucw.cz> <1214211859.8011.250.camel@pasglop> <485F7184.1030907@kernel.org> <20080623104221.3b4fb350@lxorguk.ukuu.org.uk> In-Reply-To: <20080623104221.3b4fb350@lxorguk.ukuu.org.uk> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0rc1 (hera.kernel.org [127.0.0.1]); Mon, 23 Jun 2008 13:05:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1231 Lines: 29 Alan Cox wrote: >>> BTW. Tejun, I suppose that usually starting DMA after issuing the >>> command is a standard practice of legacy/sff type controllers ? Or it's >>> just because that's how linux did it until now ? >> It's how the standard says it should be programmed. Please take a look >> at section 3 of the following document. >> >> http://www.centrillium-it.com/Projects/idems100.pdf >> >> It's a non-issue for PATA ones as the host is responsible for running > > It's very much an issue for PATA. If you start the DMA before time things > go wrong. The DMA has to start after the command is issued (or for ATAPI > after the command and the cdb are issued). Various ATAPI devices get > quite cross if you mess this up. > > In some cases the driver code also depends upon this as we software drive > the data clocks so have to reprogram them after command issue and before > data transfer begins. I was saying drive getting ready before command issue was non issue. -- tejun -- 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/