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

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Message-ID: <20120820155633.GF11013@thinkpad-t410>
Date:	Mon, 20 Aug 2012 10:56:33 -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 04:36:40PM +0100, Matthew Garrett wrote:
> On Mon, Aug 20, 2012 at 10:31:04AM -0500, Seth Forshee wrote:
> > +	/*
> > +	 * For secondary graphics devices shouldn't be initialized
> > +	 * until the handler and primary graphics device have been
> > +	 * registered with vga_switcheroo.
> > +	 *
> > +	 * FIXME: Is vga_default_device() reliable enough for this
> > +	 * purpose?
> > +	 *
> > +	 * FIXME: If vga_switcheroo is disabled secondary devices
> > +	 * never gets initialized. Is this okay? Maybe it is, since
> > +	 * we can't switch to the secondary GPU anyway.
> > +	 */
> 
> 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.

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