From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robert Hancock Subject: Re: [PATCH 2.6.32.3] ahci: AHCI and RAID mode SATA patch for Intel Cougar Point DeviceIDs Date: Wed, 13 Jan 2010 18:42:51 -0600 Message-ID: <51f3faa71001131642u2cc9de80n8e73be7a8707afb2@mail.gmail.com> References: <201001121700.18234.seth.heasley@intel.com> <4B4D4EAA.2010109@gmail.com> <4B4DAA68.60608@pobox.com> <51f3faa71001131611y343ad225n1acc73900fd49894@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-iw0-f194.google.com ([209.85.223.194]:57649 "EHLO mail-iw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751589Ab0ANAmw convert rfc822-to-8bit (ORCPT ); Wed, 13 Jan 2010 19:42:52 -0500 In-Reply-To: <51f3faa71001131611y343ad225n1acc73900fd49894@mail.gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: Seth Heasley , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, Jan 13, 2010 at 6:11 PM, Robert Hancock = wrote: > On Wed, Jan 13, 2010 at 5:11 AM, Jeff Garzik wrot= e: >>> Likely a lot of the existing specific PCI IDs could be removed from= the >>> driver because of this (many likely predate the addition of the >>> class-based catch-all). The only reason to need a specific entry if= the >>> device uses AHCI class is if it needs special handling or workaroun= ds, >>> which isn't the case here. >> >> Well, two lines of thinking here: >> >> * some of lines of Intel chips do not separate AHCI into a separate = PCI ID >> rather legacy IDE interface. =A0When an AHCI interface exists and AH= CI/IDE >> share the same PCI ID, we default to using AHCI. =A0Thus, some of th= ose PCI ID >> matches in ahci.c's PCI table may not get caught by the generic PCI = class >> match at the end of the table. > > Well, ata_piix does have a couple of entries that are listed in ahci > as well, for ICH6 device IDs 0x2652 and 0x2653. For 0x2653 ata_piix > checks the class code to make sure it's IDE, but for the 0x2652 entry= , > and in both cases in ahci, the class code isn't checked. Deleting the > specific entries from ahci for those controllers would seemingly > actually improve the situation, since then ahci wouldn't try and > attach to those devices when they indicate IDE class. ata_piix should > also should be checking for IDE class on 0x2652 as well. Hmm, it seems like it's a bit more complicated than that. For ICH6R (0x2652), ata_piix attaches to it regardless of mode intentionally, it has specific logic to disable AHCI on the controller since it can be used in either mode. That seems a bit questionable. Having the same device being handled by different enabled drivers and depending on link or module load order to decide which one loads is fragile and prone to errors. I'd be in favor of removing the ICH6R support from ata_piix entirely and saying that you should be using ahci for that device. Maybe when ahci was immature there was a benefit to allowing ata_piix to run it, but I doubt that's true today.