The BBC has learnt that the Care Quality Commission had been told of mistreatment at Winterbourne View up to two years before the alleged abuse of patients was exposed by undercover reporters at BBC Panorama.
Last year the CQC received nine reports about the care home - compared to four in the two years before.
Most of the documents - obtained under a Freedom of Information request - are official notifications of incidents at the home.
One says: "It was alleged that the support worker had squeezed the patient's neck during a restraint and that the patient had found it difficult to swallow following this incident. The patient also stated that the support worker gets rough when angry."
Another worker was reported for slapping a patient twice. Both of these staff were disciplined.
A man also rang the CQC directly raising concerns about staffing and restraint. It took three months for someone to call him back.
The CQC said the incidents were reported to local authorities and all of the incidents were appropriately reported and investigated locally.
In a statement it said: "It is the job of the local authority or the police to investigate these incidents and to hold the provider or staff to account if necessary.
"The issue at Winterbourne View was not what was known and reported, but what was concealed."
The role played by all the organisations involved with Winterbourne View is currently being examined as part of a serious case review.