On Tue, Nov 27, 2012 at 04:37:32PM +0100, Laurent Pinchart wrote:

One possibly crazy idea I had was to replace backlight devices as we know them 
with LED devices (a LED driver IC shouldn't be supported by different APIs 
depending on whether the LEDs it drives are used as a backlight or not), and 
have the panel hook up with the associated LED device to expose backlight 
operations through the CDF. Panels with a backlight controller tied to the 
panel controller (control through DSI for instance) would implement the 
backlight operations directly without instantiating a LED device. This still 
leaves the question of the userspace backlight brightness API open.

I remember looking at that before but never actually got round to it, it
seems like a sensible idea to me.