As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT RETURNED TO ATL DUE TO A LOSS OF CABIN PRESSURE. FLIGHT CREW ALSO REPORTED AN ELECTRIC SMELL AND SMOKE. CABIN OXYGEN MASKS WERE DEPLOYED. MAINTENANCE FOUND THE HIGH STAGE PILOT VALVE FAILED AND REPLACED IT. OXYGEN GENERATORS WERE REPLACED AND THE OXYGEN MASKS WERE CLEANED AND STOWED. ALL OPERATIONAL CHECKS WERE GOOD.