From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?T=F6r=F6k_Edwin?= Subject: Re: [PATCH] Add quirk to set AHCI mode on ICH boards Date: Fri, 09 Nov 2007 16:49:16 +0200 Message-ID: <4734736C.5060003@gmail.com> References: <20071109020235.GA2031@ceren> <20071109023129.GA25581@havoc.gtf.org> <4733D421.7000505@rtr.ca> <20071109034622.GB25581@havoc.gtf.org> <20071109120425.543971bf@the-village.bc.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from wx-out-0506.google.com ([66.249.82.239]:30984 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758614AbXKIOtX (ORCPT ); Fri, 9 Nov 2007 09:49:23 -0500 Received: by wx-out-0506.google.com with SMTP id h31so396552wxd for ; Fri, 09 Nov 2007 06:49:22 -0800 (PST) In-Reply-To: <20071109120425.543971bf@the-village.bc.nu> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cox Cc: Jeff Garzik , Mark Lord , Riki Oktarianto , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , linux-ide@vger.kernel.org Alan Cox wrote: > On Thu, 8 Nov 2007 22:46:22 -0500 > Jeff Garzik wrote: > > >> On Thu, Nov 08, 2007 at 10:29:37PM -0500, Mark Lord wrote: >> >>> And I might even privately patch my own kernels to map the ACHI BAR >>> in the cases where the BIOS didn't... >>> >> The inability to do this in the general case is the main reason why >> AHCI was not unconditionally enabled, even in IDE mode, when it was >> originally added... :/ >> > > We've done it all the time for various devices without problems (eg S3 > video cards). I'd like to see it go in - although perhaps attached to a > force_ahci boot param initially > There is one problem with force enabling ahci. You'll loose the CDROM on Dell laptops. Prior to force-enabling ahci there is one "device" that sees the 2 sata channels, and the 2 ide channels. When you force-enable ahci, this device becomes the ahci controller (it changes the device id), and the IDE controller will appear as a separate new device (with another device id), but it is disabled. There are registers on the ICH7 that allows you to set enabled/disabled status, but according to the documentation you should not enable a device after it has been disabled. In practice I couldn't get the CDROM to get re-enabled: * either nothing happend * spurious irqs were sent that nobody handles, unless I used irq=poll; but still no cdrom. Force-enabling AHCI, and not trying to enable the CDROM works, although I occasionally got NCQ errors. For a (long) discussion see this thread on the powertop mailing list: http://www.bughost.org/pipermail/power/2007-June/000533.html http://www.bughost.org/pipermail/power/2007-June/000573.html And there is also another slightly different approach: http://mjg59.livejournal.com/76062.html Best regards, --Edwin