As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED SMOKE IN CABIN. EMERGENCY DECLARED, RETURNED TO DFW WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED LEFT AND RIGHT AIR CYCLE MACHINE AND LEFT PACK TEMPERATURE CONTROL VALVE. ACCOMPLISHED PACK BURN. SYSTEM GROUND CHECK NORMAL OPERATION.