linux-kernel - Re: [PATCH 6/6] PM/FB/gxfb: add config option that allows disabling of VT switch during suspend

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Message-ID: <20080310230511.GA31750@elf.ucw.cz>
Date:	Tue, 11 Mar 2008 00:05:11 +0100
From:	Pavel Machek <pavel@....cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andres Salomon <dilinger@...ued.net>, adaplas@...il.com,
	linux-kernel@...r.kernel.org,
	linux-fbdev-devel@...ts.sourceforge.net, info-linux@...de.amd.com,
	jordan.crouse@....com, "Rafael J. Wysocki" <rjw@...k.pl>,
	Samuel Thibault <samuel.thibault@...-lyon.org>
Subject: Re: [PATCH 6/6] PM/FB/gxfb: add config option that allows
	disabling of VT switch during suspend

On Mon 2008-03-10 14:19:39, Andrew Morton wrote:
> On Sat, 8 Mar 2008 20:49:27 -0500
> Andres Salomon <dilinger@...ued.net> wrote:
> 
> > This is purely for suspend/resume time optimization.
> > 
> > 
> > >From 874aa20022a2501a30704163ed31a7baba7de9e5 Mon Sep 17 00:00:00 2001
> > From: Andres Salomon <dilinger@...ian.org>
> > Date: Wed, 5 Mar 2008 16:40:25 -0500
> > Subject: [PATCH] PM: add config option that allows disabling of VT switch during suspend
> > 
> > Prior to suspend, we allocate and switch to a new VT; after suspend, we
> > switch back to the original VT.  This can be slow, and is completely
> > unnecessary if the framebuffer we're using can restore video properly.
> > 
> > This adds CONFIG_DISABLE_SUSPEND_VT_SWITCH which allows the user to
> > select whether or not to do that switch.  This has been tested with the
> > gxfb driver (on a Geode GX dev board and OLPC prototype machines).  In
> > order for the user to even see this option, a framebuffer has to declare
> > support for it (via CONFIG_FBDEV_SUPPORTS_NOSWITCH).
...
> It would be far preferable to do this via a kernel boot parameter rather
> than via a kernel rebuild.

Actually, it would be better to get this right automatically, without
any config options.

And no, this is not only gxfb/lxfb.  At least Sharp Zaurus and FIC
neo1973 can suspend without switching consoles... 
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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