linux-kernel - Re: [PATCH 00/12] Thunderbolt hotplug support for Apple hardware (testers needed)

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Message-ID: <20140305002659.GA25643@srcf.ucam.org>
Date:	Wed, 5 Mar 2014 00:26:59 +0000
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Andreas Noever <andreas.noever@...il.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 00/12] Thunderbolt hotplug support for Apple hardware
 (testers needed)

On Wed, Mar 05, 2014 at 12:59:54AM +0100, Andreas Noever wrote:

> 
> I belive that the patch has the same effect as passing
>     acpi_osi=! acpi_osi=Darwin
> to the kernel. The problem with that approach is that it changes the
> firmware behaviour quite a lot. In particular it prevents Linux from
> taking over pci hotplug control:

There's not really any way around this. The method to power up the chip 
will refuse to run unless the system claims Darwin and nothing else.

> I would prefer to find a solution that boots without acpi_osi=Darwin
> as seems to trigger quite a lot of ACPI code. My current approach is
> to inject a custom OSDW method somewhere into the NHI namespace and to
> replace _PTS and _WAK from my driver. I can then wake the controller
> with the XRPE method. The last problem is that the PCI code does not
> allocate enough (or any) bus numbers below the hotplug ports. I'm
> trying to add some quirks to it but the code is not really made for
> that...

I don't think that's a workable approach - any change in the firmware 
implementation could break it. If we're going to insert quirks then I 
think it makes more sense to do it in the PCI layer rather than 
injecting things into ACPI.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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