On Thu, 30 Jun 2016, Chris Wilson wrote:

Backlights controlled by i915.ko and only associated with its connectors
and also only associated with the intel_drmfb fbcon, controlled by
i915.ko. In this situation, we already handle adjusting the backlight
when the fbcon is blanked/unblanked and do not require backlight trying
to do the same.

Attempting to register with the fbdev as a client causes lockdep to warn
about a dependency cycle:

[ ... snip ... ]

 drivers/hid/hid-picolcd_backlight.c                  |  3 ++-

For this one:

	Acked-by: Jiri Kosina [off-list ref]

-- 
Jiri Kosina
SUSE Labs