From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: libata and PATA devices Date: Sun, 7 Aug 2005 23:02:39 -0400 Message-ID: <20050808030239.GA27502@havoc.gtf.org> References: <200508071949.03782.inform@tiker.net> <42F6B8CD.4050100@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from havoc.gtf.org ([69.61.125.42]:7865 "EHLO havoc.gtf.org") by vger.kernel.org with ESMTP id S1750706AbVHHDCp (ORCPT ); Sun, 7 Aug 2005 23:02:45 -0400 Content-Disposition: inline In-Reply-To: <42F6B8CD.4050100@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: Andreas =?iso-8859-1?Q?Kl=F6ckner?= , linux-ide@vger.kernel.org On Mon, Aug 08, 2005 at 10:43:41AM +0900, Tejun Heo wrote: > I don't know much about PATA support. All I know is that ICH's seem > to generate a lot of noise in this mailing list w/ its legacy, combined, > ahci and whatever modes and no one setting seems to satisfy all. (If > anyone knows more about it, please fill in here.) Combined mode aggregates the PATA and SATA devices into a single PCI device. The chosen solution was to use the IDE driver for PATA, and libata for SATA. This was necessary since ATAPI support did not exist in libata (nor did SATAPI devices exist). An unfortunate side effect is that only one driver could have access to the busmaster DMA registers -- libata -- which meant that the IDE driver was limited to PIO data xfer for PATA. Once ATAPI support is mature in libata, we can support PATA fully in libata, and eliminate this PATA speed limitation in combined mode. Jeff