What was found
SMOKE IN THE CABIN AT GATE. THE APU WAS ON AND THE RIGHT PACK WAS ON. AFTER POWERING DOWN AIRCRAFT, SMOKE DISSIPATED. EXPEDITED DEPLANEMENT THROUGH MAIN CABIN DOOR. UPON ARRIVAL TO AIRCRAFT NO SIGN OF SMOKE/SMELL IN CABIN. ACCORDING TO FLIGHT CREW, APU AND ONLY RIGHT PACK WAS ON DURING TIME OF EVENT. COMPLIED WITH FIM. VERIFIED NO SMOKE WITH APU RUNNING AND LEFT PACK RUNNING. RECEIVED OK TO CONTINUE SERVICE. DEFERRED RIGHT PACK IAW MEL.