1
general::
Phrase(s): That will do.
That is enough.; Do no more. • That’ll do, Billy. Stop your crying. • "That will do," said Mr. Jones when he had heard enough of our arguing.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
That is enough, that will suffice, as in Please don't give me more peas; that will do, or That will do, children! There's to be no running near the pool. [Late 1800s]
American Heritage Idioms