Suspend/resume with i915.

[Edward Tomasz Napierała]

On 0123T1040, Konstantin Belousov wrote:
> On Thu, Jan 22, 2015 at 12:02:01PM +0100, Edward Tomasz Napiera??a wrote:
> > I'm trying to fix resume on my T61, broken by some change several
> > months ago; according to pciconf it's 'Mobile GM965/GL960 Integrated
> > Graphics Controller (primary)'.  It's running current CURRENT and
> > up to date packages.
> > 
> > Suspend and resume makes Xorg do something weird - there is screen
> > corruption, or rather window corruption.  The GNOME 3 desktop looks
> > pretty normal, except that gnome-terminal (launched before suspend)
> > window looks as if the buffer layout changed underneath it; for example,
> > instead of one flashing cursor there are several, horizontally, across
> > the window.  New windows are simply black.  No segv.
> > 
> > Setting kern.vt.suspendswitch=0 makes the behaviour disappear, replaced
> > by segmentation faults of gnome-shell.  With stock gdb it looks like this:
> 
> At least one big known issue with suspend is that userspace activity
> is not stopped, which makes the driver suspend code operating on the
> non-steady state of devices.
> 
> I committed the facility to stop userspace before suspend, and avg promised
> to integrate this into suspend path, but he did not.  You might try to
> search mailing lists for reference to his earlier patch.

Unfortunately stuff was committed before I could test it.  Fortunately,
it's all fixed now, and works perfectly, on 11-CURRENT.  Thanks!  :-)