EXCLUSIVE

David Otunga is back in business with his son, because he's now the primary custodial parent ... TMZ has learned.

Sources tell TMZ Jennifer Hudson and David reached a temporary custody agreement which gives him custody of 8-year-old David Jr. the majority of the time. Jennifer is currently in London shooting "The Voice UK" and she's committed to significant travel to Los Angeles to do "The Voice."

As we reported, David has said he's been his son's primary caregiver since birth because of Jennifer's travel schedule. Apparently they both now acknowledge that he will again become the primary custodial parent, at least until a formal custody agreement is worked out.

We're also told Jennifer also voluntarily dropped her order of protection, which prohibited David from having contact with their son or her.