From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] libata: add support for READ/WRITE LONG Date: Fri, 16 Mar 2007 16:38:25 -0400 Message-ID: <45FB0041.8050801@pobox.com> References: <3aac340703102322p362998b9labedc13503702d2b@mail.gmail.com> <45F56800.3040104@rtr.ca> <3aac340703121003l43685599t8dbffe6247879a91@mail.gmail.com> <45F5A523.1080500@rtr.ca> <45FA8D7A.3040504@rtr.ca> <45FAA35C.2090902@ru.mvista.com> <45FAA822.7050208@rtr.ca> <45FAAACE.6000503@ru.mvista.com> <45FAACD4.6000709@rtr.ca> <45FAAD11.9010905@rtr.ca> <45FAB662.2040901@ru.mvista.com> <20070316170802.227ff58b@lxorguk.ukuu.org.uk> <45FAE7F3.7050201@pobox.com> <45FAFB24.2050800@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:33855 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965910AbXCPUif (ORCPT ); Fri, 16 Mar 2007 16:38:35 -0400 In-Reply-To: <45FAFB24.2050800@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: Alan Cox , Sergei Shtylyov , Vitaliyi , Tejun Heo , IDE/ATA development list , Mikael Pettersson 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. > > 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. I wasn't implying a blockage of your patch, just describing a general problem within libata. Jeff