diff --git a/sys/arm/broadcom/bcm2835/bcm2835_dma.c b/sys/arm/broadcom/bcm2835/bcm2835_dma.c
--- a/sys/arm/broadcom/bcm2835/bcm2835_dma.c
+++ b/sys/arm/broadcom/bcm2835/bcm2835_dma.c
@@ -328,6 +328,9 @@
 	int ch = BCM_DMA_CH_INVALID;
 	int i;
 
+	if (sc == NULL)
+		return (BCM_DMA_CH_INVALID);
+
 	if (req_ch >= BCM_DMA_CH_MAX)
 		return (BCM_DMA_CH_INVALID);
 
@@ -343,13 +346,10 @@
 				break;
 			}
 		}
-	}
-	else {
-		if (sc->sc_dma_ch[req_ch].flags & BCM_DMA_CH_FREE) {
-			ch = req_ch;
-			sc->sc_dma_ch[ch].flags &= ~BCM_DMA_CH_FREE;
-			sc->sc_dma_ch[ch].flags |= BCM_DMA_CH_USED;
-		}
+	} else if (sc->sc_dma_ch[req_ch].flags & BCM_DMA_CH_FREE) {
+		ch = req_ch;
+		sc->sc_dma_ch[ch].flags &= ~BCM_DMA_CH_FREE;
+		sc->sc_dma_ch[ch].flags |= BCM_DMA_CH_USED;
 	}
 
 	mtx_unlock(&sc->sc_mtx);
@@ -364,6 +364,9 @@
 {
 	struct bcm_dma_softc *sc = bcm_dma_sc;
 
+	if (sc == NULL)
+		return (-1);
+
 	if (ch < 0 || ch >= BCM_DMA_CH_MAX)
 		return (-1);
 
@@ -392,6 +395,9 @@
 	struct bcm_dma_softc *sc = bcm_dma_sc;
 	struct bcm_dma_cb *cb;
 
+	if (sc == NULL)
+		return (-1);
+
 	if (ch < 0 || ch >= BCM_DMA_CH_MAX)
 		return (-1);
 
@@ -531,6 +537,9 @@
 	int i;
 	uint32_t reg;
 
+	if (sc == NULL)
+		return;
+
 	if (ch < 0 || ch >= BCM_DMA_CH_MAX)
 		return;
 
@@ -558,6 +567,9 @@
 	struct bcm_dma_softc *sc = bcm_dma_sc;
 	struct bcm_dma_cb *cb;
 
+	if (sc == NULL)
+		return (-1);
+
 	if (ch < 0 || ch >= BCM_DMA_CH_MAX)
 		return (-1);
 
@@ -597,6 +609,9 @@
 	struct bcm_dma_softc *sc = bcm_dma_sc;
 	struct bcm_dma_cb *cb;
 
+	if (sc == NULL)
+		return (0);
+
 	if (ch < 0 || ch >= BCM_DMA_CH_MAX)
 		return (0);