From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] RESEND: SCSI, libata: add support for ATA_16 commands to libata ATAPI devices Date: Thu, 01 Feb 2007 03:30:10 -0500 Message-ID: <45C1A512.8070602@garzik.org> References: <200701021935.07840.liml@rtr.ca> <200701311346.26644.liml@rtr.ca> <45C1356B.6000907@gmail.com> <45C1377F.6070001@rtr.ca> <45C138E8.1040706@gmail.com> <45C13BCD.8080003@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]:37065 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422666AbXBAIaN (ORCPT ); Thu, 1 Feb 2007 03:30:13 -0500 In-Reply-To: <45C13BCD.8080003@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: Tejun Heo , Linux IDE , James Bottomley , linux-scsi@vger.kernel.org Mark Lord wrote: > Tejun Heo wrote: >> Anyways, this has never been guaranteed because >> the limit is host wide. > > But until very very recently, "host wide" meant just a single device > for libata. I was just assuming we did all of the fiddling to ensure > a minimal value there for some real reason. > > But, yes, now we have PATA (2 drives per host), and PMP (many more > drives per host), so just maxing out the limit seems sensible. No, we can't just assume that all host controller CDB FIFOs (if indeed that's the implementation) support 16-byte CDBs. Gotta do a controller-by-controller check. There are both /host/ and /device/ limits. Jeff