dss_dpi_select_source
r = dss_dpi_select_source(dpi->dss, dpi->id, dpi->output.dispc_channel);
int dss_dpi_select_source(struct dss_device *dss, int port,
r = dss_dpi_select_source(out->port_num, out->manager->id);
int dss_dpi_select_source(int port, enum omap_channel channel);