linux-kernel - Re: [linux-pm] [PATCH] PM / i915: Skip kernel VT switch during suspend/resume if KMS is used

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Date:	Sun, 31 Jan 2010 09:54:19 +0100
From:	Pavel Machek <pavel@....cz>
To:	Stefan Seyfried <stefan.seyfried@...glemail.com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, airlied@...ux.ie,
	LKML <linux-kernel@...r.kernel.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Eric Anholt <eric@...olt.net>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	dri-devel@...ts.sourceforge.net,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [linux-pm] [PATCH] PM / i915: Skip kernel VT switch during
 suspend/resume	if KMS is used

On Thu 2010-01-28 00:07:51, Stefan Seyfried wrote:
> Hi,
> 
> On Tue, 26 Jan 2010 15:58:43 +0100 Pavel Machek <pavel@....cz> wrote:
> > We need vt switch when display is controlled by userland app directly
> > accessing hw. It may or may not be X (svgalib anyone?,
> > gtk-on-framebuffer? qtopia?).
> 
> anything-on-framebuffer should not be different from plain framebuffer
> console, or am I missing something?

It is. At least svgalib accesses hw directly. It probably can run even
on framebuffer.

> > Ideally, userspace should explicitely tell us. KD_KERNEL_GRAPHICS
> > console mode?
> > 
> > Plus the switch is needed for any graphics app using fbcon -- I do not
> > think we actually save the framebuffer over suspend. (This one should
> > probably be fixed).
> 
> Framebuffer should be easy to fix - it works pretty well already
> because apparently the fbcon code needs to "shadow buffer" all VT
> "windows" anyway - so maybe it's just the issue of doing an additional
> "redraw()" somewhere appropriate.

Well, for now the "shadow buffer" contains only text, not graphics
images. So you'd need to enlarge it a lot. Doable but more than one liner.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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