I have mecool tv box connected with hdmi and samsung tv connected as well. when i gave standby command using adb my tv goes to standby but when i gave any other commands it can't work. e.g
# echo 0x40 0x36 > /sys/class/cec/cmd
this command working for standby.
# echo 0x40 0x8F> /sys/class/cec/cmd
# echo 0x80 0x82> /sys/class/cec/cmd
these commands didn't display anything on screen or tv. i am taking help about commands from this website cec-o-matic