Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759532AbXFMSlS (ORCPT ); Wed, 13 Jun 2007 14:41:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759340AbXFMSks (ORCPT ); Wed, 13 Jun 2007 14:40:48 -0400 Received: from rtr.ca ([64.26.128.89]:3338 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754934AbXFMSkq (ORCPT ); Wed, 13 Jun 2007 14:40:46 -0400 Message-ID: <46703A2D.6000207@rtr.ca> Date: Wed, 13 Jun 2007 14:40:45 -0400 From: Mark Lord User-Agent: Thunderbird 2.0.0.0 (X11/20070326) MIME-Version: 1.0 To: albertl@mail.com Cc: Alan Cox , Jeff Garzik , Linux Kernel Mailing List , IDE/ATA development list Subject: Re: libata passthru: support PIO multi commands References: <200706112200.l5BM0qFn005767@hera.kernel.org> <20070611233917.4bd8c6d7@the-village.bc.nu> <466DE438.70108@garzik.org> <20070612111621.10074408@the-village.bc.nu> <466EB937.6050807@garzik.org> <20070612170519.5f427a70@the-village.bc.nu> <466F5D11.7000404@tw.ibm.com> In-Reply-To: <466F5D11.7000404@tw.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1404 Lines: 37 Albert Lee wrote: > .. > It looks like the ATA passthru commands contain more information than > what libata needs to execute a command. > > e.g. protocol number: > libata could possibly infer the protocol from the command opcode. > > e.g. multi_count: > libata caches dev->multi_count. Passing multi_count along with > each passthru command looks useless for libata. > > e.g. t_dir: > libata could possible infer the direction from the command opcode > or from the protocol number (e.g. 4: PIO_IN / 5: PIO_OUT). I wonder if the *intent* of the specification was that the low-level driver should perform whatever setup is necessary to issue the command as given. So if the command specifies a multcount of 8, then the LLD should issue the appropriate initialization commands to use a multcount of 8, and then issue the given R/W MULT command, and then perhaps reset the multcount back to what it was normally (beforehand) ? Ditto for the others. I am *not* proposing that we actually do it this way, but rather just suggesting a possible rationale. What does the SAT spec say? Any further hints as to the intent? Cheers - 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/