diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 7c574901ad1c..2e1783ae8a9b 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -3358,6 +3358,22 @@ static int sci_probe_single(struct platform_device *dev,
 	}
 
 	if (sci_uart_earlycon && sci_ports[0].port.mapbase == sci_res->start) {
+		/*
+		 * In case:
+		 * - this is the earlycon port (mapped on index 0 in sci_ports[]) and
+		 * - it now maps to an alias other than zero and
+		 * - the earlycon is still alive (e.g., "earlycon keep_bootcon" is
+		 *   available in bootargs)
+		 *
+		 * we need to avoid disabling clocks and PM domains through the runtime
+		 * PM APIs called in __device_attach(). For this, increment the runtime
+		 * PM reference counter (the clocks and PM domains were already enabled
+		 * by the bootloader). Otherwise the earlycon may access the HW when it
+		 * has no clocks enabled leading to failures (infinite loop in
+		 * sci_poll_put_char()).
+		 */
+		pm_runtime_get_noresume(&dev->dev);
+
 		/*
 		 * Skip cleanup the sci_port[0] in early_console_exit(), this
 		 * port is the same as the earlycon one.