Comment 6 for bug 1133168

We need this patch to fix the pre-existing bug that will make the screen become black.
But, this commit based on many other changes.

commit 3739850b46f560a2be29287c3e5c29999d1a7e0e
Author: Daniel Vetter <email address hidden>
Date: Thu Sep 6 22:15:44 2012 +0200

    drm/i915: disable the cpu edp port after the cpu pipe

    See bspec, Vol3 Part2, Section 1.1.3 "Display Mode Set Sequence". This
    applies to all platforms where we currently support eDP on, i.e. ilk,
    snb & ivb.

    Without this change we fail to light up the eDP port on previously
    unused crtcs (likely because something is stuck on the old pipe), and
    we also fail to properly disable the old pipe (i.e. bit 30 in the
    PIPECONF register is stuck as set until the next reboot).

    v2: Rebased on top of the edp panel off sequence changes in 3.6-rc2.

    Reviewed-by: Paulo Zanoni <email address hidden>
    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=44001
    Signed-Off-by: Daniel Vetter <email address hidden>