diff --git a/share/man/man4/psm.4 b/share/man/man4/psm.4
index ad4f5f24d92d..2324598c2848 100644
--- a/share/man/man4/psm.4
+++ b/share/man/man4/psm.4
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 26, 2016
+.Dd June 2, 2020
 .Dt PSM 4
 .Os
 .Sh NAME
@@ -361,6 +361,15 @@ the sysctl with the same name and by restarting
 .Xr moused 8
 using
 .Pa /etc/rc.d/moused .
+.Pp
+Active multiplexing support can be disabled by setting
+.Va hw.psm.mux_disabled
+to
+.Em 1
+at boot-time.
+This will prevent
+.Nm
+from enabling active multiplexing mode needed for some Synaptics touchpads.
 .Sh IOCTLS
 There are a few
 .Xr ioctl 2
diff --git a/sys/dev/atkbdc/psm.c b/sys/dev/atkbdc/psm.c
index a8384b370f6c..f7e94b474cb9 100644
--- a/sys/dev/atkbdc/psm.c
+++ b/sys/dev/atkbdc/psm.c
@@ -517,6 +517,7 @@ static int verbose = PSM_DEBUG;
 static int synaptics_support = 1;
 static int trackpoint_support = 1;
 static int elantech_support = 1;
+static int mux_disabled = 0;
 
 /* for backward compatibility */
 #define	OLD_MOUSE_GETHWINFO	_IOR('M', 1, old_mousehw_t)
@@ -2989,6 +2990,9 @@ SYSCTL_INT(_hw_psm, OID_AUTO, trackpoint_support, CTLFLAG_RDTUN,
 SYSCTL_INT(_hw_psm, OID_AUTO, elantech_support, CTLFLAG_RDTUN,
     &elantech_support, 0, "Enable support for Elantech touchpads");
 
+SYSCTL_INT(_hw_psm, OID_AUTO, mux_disabled, CTLFLAG_RDTUN,
+    &mux_disabled, 0, "Disable active multiplexing");
+
 static void
 psmintr(void *arg)
 {
@@ -6293,6 +6297,9 @@ enable_synaptics_mux(struct psm_softc *sc, enum probearg arg)
 	int active_ports_count = 0;
 	int active_ports_mask = 0;
 
+	if (mux_disabled != 0)
+		return (FALSE);
+
 	version = enable_aux_mux(kbdc);
 	if (version == -1)
 		return (FALSE);
@@ -6330,6 +6337,21 @@ enable_synaptics_mux(struct psm_softc *sc, enum probearg arg)
 	/* IRQ handler does not support active multiplexing mode */
 	disable_aux_mux(kbdc);
 
+	/* Is MUX still alive after switching back to legacy mode? */
+	if (!enable_aux_dev(kbdc) || !disable_aux_dev(kbdc)) {
+		/*
+		 * On some laptops e.g. Lenovo X121e dead AUX MUX can be
+		 * brought back to life with resetting of keyboard.
+		 */
+		reset_kbd(kbdc);
+		if (!enable_aux_dev(kbdc) || !disable_aux_dev(kbdc)) {
+			printf("psm%d: AUX MUX hang detected!\n", sc->unit);
+			printf("Consider adding hw.psm.mux_disabled=1 to "
+			    "loader tunables\n");
+		}
+	}
+	empty_both_buffers(kbdc, 10);	/* remove stray data if any */
+
 	return (probe);
 }