This supersedes (1). The first patch fixes the tegra-video driver: it now creates the new controls for the control handler first, before calling v4l2_ctrl_add_handler(). This prevents a warning, which is introduced in the next patch. The second patch checks for adding a duplicate control to the same handler, and returns an error, but it also adds a warning if new controls are added to a handler after v4l2_ctrl_add_handler() is called. Eventually this sequence should result in an error instead of a warning, but I feel it is better to keep the warning for a few kernel cycles to make sure any broken driver is fixed.
