[Intel-gfx] [PATCH] drm/i915: Only unbind vgacon, not other console drivers

[Chris Wilson]

On Tue, Jul 08, 2014 at 10:08:37AM +0200, Daniel Vetter wrote:
> The console subsystem only provides a function to switch to a given
> console, but we want to actually only switach away from vgacon.
> Unconditionally switching to the dummy console resulted in switching
> away from fbcon in multi-gpu setups when other gpu drivers are loaded
> before i915.
> 
> Then either the reinitialization of fbcon when i915 registers its
> fbdev emulation or the teardown of the fbcon driver killed the
> machine. So only switch to the dummy console when it's required.
> 
> Kudos to Chris for the original idea, I've only refined it a bit to
> still unregister vgacon even when it's currently unused.
> 
> This regression has been introduced in
> 
> commit a4de05268e674e8ed31df6348269e22d6c6a1803
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Thu Jun 5 16:20:46 2014 +0200
> 
>     drm/i915: Kick out vga console
> 
> Reported-and-tested-by: Ed Tomlinson <edt at aei.ca>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: David Herrmann <dh.herrmann at gmail.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

I checked that do_unregister_con_driver(&vga_con) is a no-op, and it is
definitely a horrible idea to mix vga_con and vgaarb, so it has to go.

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre