diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 8b3756e4bb05..f648fd1d7548 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1023,7 +1023,8 @@ static void autoconfig_16550a(struct uart_8250_port *up)
 	up->port.type = PORT_16550A;
 	up->capabilities |= UART_CAP_FIFO;
 
-	if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS))
+	if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS) &&
+	    !(up->port.flags & UPF_FULL_PROBE))
 		return;
 
 	/*
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 59a8caf3230a..6df4c3356ae6 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -100,7 +100,7 @@ struct uart_icount {
 	__u32	buf_overrun;
 };
 
-typedef unsigned int __bitwise upf_t;
+typedef u64 __bitwise upf_t;
 typedef unsigned int __bitwise upstat_t;
 
 struct uart_port {
@@ -207,6 +207,7 @@ struct uart_port {
 #define UPF_FIXED_PORT		((__force upf_t) (1 << 29))
 #define UPF_DEAD		((__force upf_t) (1 << 30))
 #define UPF_IOREMAP		((__force upf_t) (1 << 31))
+#define UPF_FULL_PROBE		((__force upf_t) (1ULL << 32))
 
 #define __UPF_CHANGE_MASK	0x17fff
 #define UPF_CHANGE_MASK		((__force upf_t) __UPF_CHANGE_MASK)