Add a reset interface

[Takashi Iwai]

At Mon, 24 Jan 2011 15:55:27 +0000,
Chris Wilson wrote:
> 
> For i915 there is a need to invalidate some cached state after resuming or
> reseting the GPU. This is not quite the same as simply restoring saved
> state (i.e. the standard suspend resume method), so do not seem to merit
> reusing the save|restore vfuncs.  Instead I propose a
> 
>    drm_mode_config_reset(struct drm_device *);
> 
> routine to iterate over all the attached CRTCs, encoders and connectors
> and call any supplied reset vfunc.
> 
> This is required to fix some modesetting regressions across resume in
> 2.6.38:
> https://bugzilla.kernel.org/show_bug.cgi?id=26952
> https://bugzilla.kernel.org/show_bug.cgi?id=27272

I quickly tried these patches.  After adding the missing EXPORT_SYMBOL,
it seems working fine.  Tested on a SNB laptop and a PineView laptop.

Put my tag to all patches:
  Tested-by: Takashi Iwai <tiwai at suse.de>
  

Thanks!

Takashi