From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: ata_piix failure on ich6m Date: Fri, 12 May 2006 23:42:34 -0400 Message-ID: <446555AA.9000603@pobox.com> References: <20060510235650.GA20206@srcf.ucam.org> <44629E68.3020302@gmail.com> 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]:37089 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S932174AbWEMDml (ORCPT ); Fri, 12 May 2006 23:42:41 -0400 In-Reply-To: <44629E68.3020302@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: Matthew Garrett , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Tejun Heo wrote: > Matthew Garrett wrote: >> Hi, >> >> We've got an ich6m system (a Toshiba Portege S100). ata_piix attempts >> to drive the chipset, but fails - however, it doesn't bail out. As a >> result it remains bound to the device and ahci isn't loaded. >> >> I've attached the lspci output for the chipset. A few things to note are: >> >> 1) The AHCI BAR is set >> 2) The SCC register identifies it as an AHCI controller >> 3) Bits 2 and 0 of the PCS are set, which the spec claims indicates >> that the port is to be controlled as an ahci device. >> >> So, my question is effectively: why does ata_piix attempt to disable >> ahci rather than simply letting the ahci driver bind? Points (1) and >> (2) seem to be checked by the code, but I'm guessing that in the case >> of (3) it should just return ENODEV and let ahci be run instead. If >> so, should I code up a patch? >> > > I'm not very sure but it might be historical. ahci got implemented > after ata_piix and in the meantime ata_piix must have handled all it > could. Can you verify whether modifying the code to return -ENODEV work > for your machine? If so, that could be the correct solution but I'm a > bit worried because it could change probing order or fail to enable > devices it used to. Maybe we need a hack to return -ENODEV iff ahci is > there to handle the device. It's definitely historical. I'm pretty frazzled now so I don't remember. It may be that on ICH6, AHCI mode does not cause the PCI IDs to change, so driver load order winds up dictating what gets used. Jeff