From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: ata_piix failure on ich6m Date: Thu, 11 May 2006 11:16:08 +0900 Message-ID: <44629E68.3020302@gmail.com> References: <20060510235650.GA20206@srcf.ucam.org> 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 ([64.233.166.180]:54976 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S1751524AbWEKCQO (ORCPT ); Wed, 10 May 2006 22:16:14 -0400 Received: by py-out-1112.google.com with SMTP id f28so90489pyf for ; Wed, 10 May 2006 19:16:13 -0700 (PDT) In-Reply-To: <20060510235650.GA20206@srcf.ucam.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Matthew Garrett Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, jgarzik@pobox.com 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. -- tejun