When o Access Point was in Autonomous, the interface was "state up protocol down" in "show int g0", so I change manually speed/duplex (100/full) and was "state up protocol up", so converting the Access Point from Autonomous to Lightweight and happenedthe same problem ("state up protocol down")!
What command for configure speed/duplex in interface when Access Point is mode Lightweight?
By the way, your solution of setting the interface and the speed (on the AP) is just temporary measure. The minute you reboot your AP your problem will return. Why do you think all of us who's recommending the solution is focusing on the switch?