From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: Kernel Summit request for Discussion of future of ATA (libata) and IDE Date: Wed, 06 Aug 2008 15:17:38 +0400 Message-ID: <48998852.30603@ru.mvista.com> References: <48976168.3020804@shaw.ca> <20080804205508.20a3f917@lxorguk.ukuu.org.uk> <48977AE1.1070402@ru.mvista.com> <20080804224309.77ffd28e@lxorguk.ukuu.org.uk> <489786A7.8060400@ru.mvista.com> <4897883F.6020007@ru.mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from h155.mvista.com ([63.81.120.155]:39670 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1759158AbYHFLRr (ORCPT ); Wed, 6 Aug 2008 07:17:47 -0400 In-Reply-To: <4897883F.6020007@ru.mvista.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Sergei Shtylyov Cc: Alan Cox , Robert Hancock , Bartlomiej Zolnierkiewicz , James Bottomley , ksummit-2008-discuss@lists.linux-foundation.org, linux-kernel , linux-ide Hello, I wrote: >>>>>> supported. I couldn't track down where that bit was actually >>>>>> defined in the first place, all the way back to ATA-1 it seems to >>>>>> be indicated as reserved. Actually, I'm not sure why the drive >>>>>> cares in the first place, it would seem like a pure host >>>>>> controller issue.. >>>>>> >>>>> It goes back before IDE into the depths of the original compaq >>>>> spec. When >>>>> you have a device wired basically directly to the ISA bus >>>>> (original IDE) >>>>> >>>> ISA has only 8/16-bit data bus, so it could not have mattered >>>> there... >>> >>> Depends what a 32bit I/O looks like on the 16bit bus - timing wise. >>> >> >> Two 16-bit reads at addresses 0x1x0 and 0x1x2 with the programmed >> recovery time, IIRC... It's just occured to me that in case of the >> 16-bit bus it should be how the drive treated the accesses at address >> 0x1x2 with IOCS16 asserted that could have mattered. If it honored >> them, 32-bit I/O could have worked even on a dumb ISA "controller", >> if not -- no way (unless you really had *something* between the ISA >> and the IDE cable). > > Oh, -IOCS16 is driven by device, not host. I give up then. :-) > OTOH, it definitely could work if the drive asserted it for the I/O port 0x1x2 at least for the data transfer phase (and probably even if it always asserted -IOCS16 for this address). That pre-historic word indeed could have made sense then... MBR, Sergei