my xperia u phone having brightness issue. The brightness actully get stucks at a quantity and after that it do not get increase or decrease and after a perticular time period it works proprely but it come back after few day and the cycle is on..
If you have "adapt to lightning conditions" activated I suggest that you try to deactivate it and restart the phone to see if you experience the same problem.
You can also try to start your phone in safe mode to see if the problem you are experiencing is caused by a 3rd party application installed in your phone.
