From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Subject: Re: [PATCH] libata: add support for READ/WRITE LONG Date: Fri, 16 Mar 2007 22:09:13 +0100 Message-ID: <200703162209.13411.bzolnier@gmail.com> References: <3aac340703102322p362998b9labedc13503702d2b@mail.gmail.com> <45FAE7F3.7050201@pobox.com> <45FAFB24.2050800@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from ug-out-1314.google.com ([66.249.92.171]:41561 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965926AbXCPVB6 (ORCPT ); Fri, 16 Mar 2007 17:01:58 -0400 Received: by ug-out-1314.google.com with SMTP id 44so803481uga for ; Fri, 16 Mar 2007 14:01:57 -0700 (PDT) In-Reply-To: <45FAFB24.2050800@rtr.ca> Content-Disposition: inline Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: Jeff Garzik , Alan Cox , Sergei Shtylyov , Vitaliyi , Tejun Heo , IDE/ATA development list , Mikael Pettersson On Friday 16 March 2007, Mark Lord wrote: > Jeff Garzik wrote: > > Alan Cox wrote: > >>> I think it only requires the *host* to drop to PIO0 timings. In > >>> which case it should be achievable w/o libata modification -- if the > >>> driver has to "snoop" command and turn off prefetch, why not switch > >>> to PIO0 temporarily? > >> > >> This isn't a big issue. Eventually we have to support sending speed > >> change commands and once we do that the caller will be able to switch to > >> PIO0 and back again. > > > > We should be pretty close to that. One of the bigger blockages is > > needing to stop (freeze) all ports, before performing an out-of-band SET > > FEATURES and related tuning. > > For this particular feature, READ/WRITE LONG, > none of this is actually necessary in practice on common controllers. It still would be nice to add a comment documenting issues raised by Sergei so if somebody actually hits a problem on not-so-common controller she/he will know what to look for. > I've tested ATA1 and newer PATA drives, and various SATA drives > with these commands without bothering to drop to PIO0, > and none of them had issues. This is what really matters wrt libata READ/WRITE LONG support. These commands are not supposed to be used by normal users anyway so patch while not being "perfect" is "good enough" to be merged IMO. Bart