Davis appeared in an Orange County courtroom this morning -- where he also pled not guilty to two lesser drug charges.
As TMZ first reported, the "Celebrity Rehab" star was popped in Newport Beach, CA and cops believe he was high on a "central nervous system stimulant (prescription meds) and narcotic analgesic (painkillers) at the time of his arrest.
If convicted, Davis could face up to 3 years behind bars.