linux-kernel - Re: [PATCH] apple-gmux: Restore switch registers on suspend/resume

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Date:	Wed, 01 Aug 2012 18:06:10 +0200
From:	Andreas Heider <andreas@...tr.de>
To:	David Woodhouse <dwmw2@...radead.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Arun Raghavan <arun.raghavan@...labora.co.uk>,
	linux-kernel@...r.kernel.org, airlied@...hat.com
Subject: Re: [PATCH] apple-gmux: Restore switch registers on suspend/resume

Am 01.08.12 17:59, schrieb Seth Forshee:
> On Wed, Aug 01, 2012 at 04:35:44PM +0100, David Woodhouse wrote:
>> On Tue, 2012-07-31 at 10:18 -0500, Seth Forshee wrote:
>>>
>>> All of this is working to the extent that I can boot with the Radeon
>>> card active, switch over to the Intel card, and get the EDID for the
>>> internal panel and an external monitor (although oddly on an HDMI
>>> connector, no on the DP like I expected). Both screens are remaining
>>> blank though. However I'm also getting blank screens if I mux over to
>>> the Intel GPU from grub before loading the kernel, which used to work
>>> for the LVDS panel at least.
>>
>> Hm, when I was changing over to the external screen before boot, I could
>> get the LVDS working but *not* an external VGA or DVI monitor (via the
>> standard Apple adaptors). Should I expect that to work if I change the
>> mux 'properly' at runtime?
>
> I don't think the mini-DP port works at all with the integrated
> graphics, at least not on a Macbook Pro 8,2. I played around with it
> yesterday under OS X. When using the DGPU with an external monitor it
> works fine, but any attempts to switch to the IGPU were rejected by the
> drivers. If I forced it to the IGPU prior to connecting the external
> monitor the screen just remained blank when I plugged it in, until I
> switched back to the DGPU. It's odd though that the DDC can be switched
> over to the IGPU.

The situation is a bit different on the Macbook Pro 6,2. OS X also 
automatically switches to the DGPU when an external monitor is 
connected, but unlike the 8,2, the IGPU works fine under Linux with 
external monitors if port 0x740 is set accordingly. I'm pretty sure that 
this is also the case with for the older macbooks without dynamic switching.

> Iirc you've got the 8,3, and I'd expect it to be identical to the 8,2 in
> this respect. Also, the only reason my LVDS didn't work was because I
> wasn't telling i915 to disable SSC. I've got a patch to add a quirk for
> this that I'll send soon, since there still doesn't seem to be any way
> to get the vbios for the Intel graphics.
>
> Seth
>

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