[Intel-gfx] Regression in drm-intel caused by d91a2cb8e510

[Damien Lespiau]

On Mon, Sep 01, 2014 at 04:19:23PM -0400, Alan Stern wrote:
> Daniel:
> 
> I'm encountering a problem with the drm-intel-nightly branch in your
> drm-intel repository.  The symptom is that when I boot my laptop, at
> some point during the start-up procedure the screen goes totally blank,
> as though the backlight were turned off, and it remains that way.  I
> can't tell if the backlight really is off -- it may be that there's
> just nothing being displayed -- and playing with the screen-brightness
> function keys doesn't help.
> 
> Git bisect located the source of the problem as commit d91a2cb8e510
> (drm/i915: Add 180 degree primary plane rotation support).  The problem
> occurs when I boot a kernel built from that commit, and it doesn't
> occur when I boot a kernel built from the preceding commit
> (19ac737dc3c3).
> 
> If necessary, I can get debugging info by logging in over a network 
> connection.  Tell me what you need.

It seems like Ville and Mika already caught a similar bug today, could
you give Ville's patch a go (available on the intel-gfx):

  drm/i915: Don't call intel_plane_restore() when the prop value didn't change


Thanks,

-- 
Damien