HAL doesn't seem to support Dell's Ambient Light Sensor. It can be used, in
hardware, by pressing Fn+Left arrow (auto brightness), and it will adjust the
display brightness automatically.
Created attachment 153411 [details]
Can be solved by writing an addon implementing this interface
I did that in one day for my Macbook Pro... It's probably better to track this
upstream; care to file a bug at fd.o and close this as UPSTREAM with a reference
to that? Thanks!
Filed upstream at: