diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index efe53dfcac3b..2c7c9cea0f3b 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1698,13 +1698,15 @@ static struct regmap_config regcfg = {
 	.max_register = SC16IS7XX_EFCR_REG,
 };
 
-static const char *sc16is7xx_regmap_name(unsigned int port_id)
+static const char *sc16is7xx_regmap_name(u8 port_id)
 {
-	static char buf[6];
-
-	snprintf(buf, sizeof(buf), "port%d", port_id);
-
-	return buf;
+	switch (port_id) {
+	case 0:	return "port0";
+	case 1:	return "port1";
+	default:
+		WARN_ON(true);
+		return NULL;
+	}
 }
 
 static unsigned int sc16is7xx_regmap_port_mask(unsigned int port_id)