The audio programming sequence states that the ELD must be written and
enabled after the pipe is ready. Indeed, this should clarify the
situation with

commit c7905792
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Apr 16 16:56:09 2014 +0200

    drm/i915: Remove vblank wait from haswell_write_eld

and Ville's review of it [1].

Moreover, we should not touch the relevant registers before we get the
audio power domain.

[1] http://mid.gmane.org/20140416155309.GK18465@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>