diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 3a1473bf54d0..137175aa4183 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -711,6 +711,9 @@ static int omap_8250_startup(struct uart_port *port)
 	struct uart_8250_dma *dma = &priv->omap8250_dma;
 	int ret;
 
+	/* ISR and runtime PM need the line; probe sets it only after registration */
+	priv->line = port->line;
+
 #ifdef CONFIG_PM
 	up->capabilities |= UART_CAP_RPM;
 #endif