Index: sys/dev/nvme/nvme_ctrlr.c
===================================================================
--- sys/dev/nvme/nvme_ctrlr.c
+++ sys/dev/nvme/nvme_ctrlr.c
@@ -247,21 +247,25 @@
 	cc.raw = nvme_mmio_read_4(ctrlr, cc);
 	csts.raw = nvme_mmio_read_4(ctrlr, csts);
 
-	if (cc.bits.en != desired_val) {
-		nvme_printf(ctrlr, "%s called with desired_val = %d "
-		    "but cc.en = %d\n", __func__, desired_val, cc.bits.en);
-		return (ENXIO);
+	ms_waited = 0;
+	while (cc.bits.en != desired_val) {
+		if (ms_waited++ > ctrlr->enable_timeout_in_ms) {
+			nvme_printf(ctrlr, "controller enable did not become %d "
+			    "within %d ms\n", desired_val, ctrlr->enable_timeout_in_ms);
+			return (ENXIO);
+		}
+		DELAY(1000);
+		cc.raw = nvme_mmio_read_4(ctrlr, cc);
 	}
 
 	ms_waited = 0;
-
 	while (csts.bits.rdy != desired_val) {
-		DELAY(1000);
 		if (ms_waited++ > ctrlr->ready_timeout_in_ms) {
 			nvme_printf(ctrlr, "controller ready did not become %d "
 			    "within %d ms\n", desired_val, ctrlr->ready_timeout_in_ms);
 			return (ENXIO);
 		}
+		DELAY(1000);
 		csts.raw = nvme_mmio_read_4(ctrlr, csts);
 	}
 
@@ -282,7 +286,6 @@
 
 	cc.bits.en = 0;
 	nvme_mmio_write_4(ctrlr, cc, cc.raw);
-	DELAY(5000);
 	nvme_ctrlr_wait_for_ready(ctrlr, 0);
 }
 
@@ -326,7 +329,6 @@
 	cc.bits.mps = (PAGE_SIZE >> 13);
 
 	nvme_mmio_write_4(ctrlr, cc, cc.raw);
-	DELAY(5000);
 
 	return (nvme_ctrlr_wait_for_ready(ctrlr, 1));
 }
@@ -1123,6 +1125,7 @@
 	/* Get ready timeout value from controller, in units of 500ms. */
 	cap_lo.raw = nvme_mmio_read_4(ctrlr, cap_lo);
 	ctrlr->ready_timeout_in_ms = cap_lo.bits.to * 500;
+	ctrlr->enable_timeout_in_ms = 2500; /* Wait up to 2.5s for EN bit delta */
 
 	timeout_period = NVME_DEFAULT_TIMEOUT_PERIOD;
 	TUNABLE_INT_FETCH("hw.nvme.timeout_period", &timeout_period);
Index: sys/dev/nvme/nvme_private.h
===================================================================
--- sys/dev/nvme/nvme_private.h
+++ sys/dev/nvme/nvme_private.h
@@ -246,6 +246,7 @@
 	struct mtx		lock;
 
 	uint32_t		ready_timeout_in_ms;
+	uint32_t		enable_timeout_in_ms;
 
 	bus_space_tag_t		bus_tag;
 	bus_space_handle_t	bus_handle;