title: Write something to linux hid device?
body: <p>I am learning linux hid driver programming, i know how to read a message from hid device<br>
  but, i am puzzled how to write something to the device ? such as usb hid keyboard, i can use
  xset or some other program to control the leds of the keyboard, how to archive that? Any tips  please!<br>
  thanks advance.</p>