linux-kernel - Re: [RFC PATCH 7/7] drm/pci: Defer initialization of secondary graphics devices until switcheroo is ready

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Date:	Mon, 20 Aug 2012 11:24:44 -0500
From:	Seth Forshee <seth.forshee@...onical.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	Dave Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Andreas Heider <andreas@...tr.de>
Subject: Re: [RFC PATCH 7/7] drm/pci: Defer initialization of secondary
 graphics devices until switcheroo is ready

On Mon, Aug 20, 2012 at 04:57:41PM +0100, Matthew Garrett wrote:
> On Mon, Aug 20, 2012 at 10:56:33AM -0500, Seth Forshee wrote:
> > On Mon, Aug 20, 2012 at 04:36:40PM +0100, Matthew Garrett wrote:
> > > Won't this break the multiple cards with independent outputs case?
> > 
> > Yes, if they don't have a switcheroo handler. I only have experience
> > with one such machine, which had optimus graphics. My recollection is
> > that it did have a switcheroo handler, which was only capable of
> > controlling power to the discrete card.
> 
> So if I have a desktop machine and install two graphics cards?

Yeah, that would likely be broken.

I'm not sure how we support both of these cases without doing something
more like what I originally proposed, i.e. registering the LVDS
connector even if it doesn't look like a panel is attached. I still
honestly favor that approach, although it does come with its own set of
challenges.

The only other option I can come up with is to reprobe LVDS after
switcheroo and add the connector at that time. I haven't investigated
this option in detail, but at first glance it looks like there are at
least some places where DRM isn't prepared to cope with adding
connectors after initialization.

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