From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFC] AHCI Command Completion Coalescing(CCC) proposal Date: Fri, 09 Jun 2006 14:24:18 +0900 Message-ID: <44890602.90002@gmail.com> References: <1149751860.29552.79.camel@forrest26.sh.intel.com> <44883BAE.7070406@pobox.com> <1149820043.5721.7.camel@forrest26.sh.intel.com> <4488EB4A.4050501@pobox.com> <4488EE69.7050907@gmail.com> <4488EF64.9070602@gmail.com> <1149825065.5721.22.camel@forrest26.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from py-out-1112.google.com ([64.233.166.176]:5457 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S965173AbWFIFYY (ORCPT ); Fri, 9 Jun 2006 01:24:24 -0400 Received: by py-out-1112.google.com with SMTP id x31so854322pye for ; Thu, 08 Jun 2006 22:24:24 -0700 (PDT) In-Reply-To: <1149825065.5721.22.camel@forrest26.sh.intel.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: "zhao, forrest" Cc: Jeff Garzik , linux-ide@vger.kernel.org zhao, forrest wrote: > On Fri, 2006-06-09 at 12:47 +0900, Tejun Heo wrote: >> If we're gonna do it. EH needs only a few changes probably during >> autopsy and report. Fixing up command issue path and implementing >> command exclusion (NCQ vs. non-NCQ, sil24 does it in hardware, ahci >> doesn't) will be a bit complex though. > > Would you please elaborate on command exclusion? Why NCQ commands need > to be excluded from non-NCQ commands? AHCI spec rev 1.1, sect 1.7. The last paragraph says. "This multiple-use of the command list is achieved by the HBA only moving its command list pointer when the BSY, DRQ, and ERR bits are cleared by the device. System software is responsible to ensure that queued and non-queued commands are not mixed in the command list." -- tejun