diff --git a/sys/dev/sdhci/sdhci.c b/sys/dev/sdhci/sdhci.c
--- a/sys/dev/sdhci/sdhci.c
+++ b/sys/dev/sdhci/sdhci.c
@@ -715,34 +715,39 @@
 
 	SDHCI_LOCK(slot);
 	present = SDHCI_GET_CARD_PRESENT(slot->bus, slot);
-	if (present && slot->dev == NULL) {
+	d = slot->dev;
+	SDHCI_UNLOCK(slot);
+
+	if (present && d == NULL) {
 		/* If card is present - attach mmc bus. */
 		if (bootverbose || sdhci_debug)
 			slot_printf(slot, "Card inserted\n");
 
-		d = slot->dev = device_add_child(slot->bus, "mmc",
-		    DEVICE_UNIT_ANY);
-		SDHCI_UNLOCK(slot);
-		if (d) {
+		d = device_add_child(slot->bus, "mmc", DEVICE_UNIT_ANY);
+		if (d != NULL) {
 			device_set_ivars(d, slot);
 			(void)device_probe_and_attach(d);
 		}
-	} else if (!present && slot->dev != NULL) {
-		d = slot->dev;
+
+		SDHCI_LOCK(slot);
+		slot->dev = d;
+		SDHCI_UNLOCK(slot);
+	} else if (!present && d != NULL) {
 		/* If no card present - detach mmc bus. */
 		if (bootverbose || sdhci_debug)
 			slot_printf(slot, "Card removed\n");
 
+		SDHCI_LOCK(slot);
 		slot->dev = NULL;
 		slot->intmask &= ~sdhci_tuning_intmask(slot);
 		WR4(slot, SDHCI_INT_ENABLE, slot->intmask);
 		WR4(slot, SDHCI_SIGNAL_ENABLE, slot->intmask);
 		slot->opt &= ~SDHCI_TUNING_ENABLED;
 		SDHCI_UNLOCK(slot);
+
 		callout_drain(&slot->retune_callout);
 		device_delete_child(slot->bus, d);
-	} else
-		SDHCI_UNLOCK(slot);
+	}
 }
 #endif /* MMCCAM */