Re: [PATCH] Add quirk to set AHCI mode on ICH boards

[Riki Oktarianto <rkoktarianto@gmail.com>]

On Fri, Nov 09, 2007 at 04:49:16PM +0200, Török Edwin wrote:
> 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
> 

In the MacBook, after enabling ahci the IDE controller also appeared as a
separate new device, but it is enabled and handled correctly by piix.

I haven't got any problem, even suspend/resume works fine.

Lucky us who got the ABAR mapped by the BIOS...

-- 
Riki Oktarianto