1 files changed, 18 insertions, 15 deletions

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 847f84a41a69..f84e20ca3d97 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -421,7 +421,12 @@ static int bcm2835_dma_abort(void __iomem *chan_base)
 	long int timeout = 10000;
 
 	cs = readl(chan_base + BCM2835_DMA_CS);
-	if (!(cs & BCM2835_DMA_ACTIVE))
+
+	/*
+	 * A zero control block address means the channel is idle.
+	 * (The ACTIVE flag in the CS register is not a reliable indicator.)
+	 */
+	if (!readl(chan_base + BCM2835_DMA_ADDR))
 		return 0;
 
 	/* Write 0 to the active bit - Pause the DMA */
@@ -485,8 +490,15 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
 
 	spin_lock_irqsave(&c->vc.lock, flags);
 
-	/* Acknowledge interrupt */
-	writel(BCM2835_DMA_INT, c->chan_base + BCM2835_DMA_CS);
+	/*
+	 * Clear the INT flag to receive further interrupts. Keep the channel
+	 * active in case the descriptor is cyclic or in case the client has
+	 * already terminated the descriptor and issued a new one. (May happen
+	 * if this IRQ handler is threaded.) If the channel is finished, it
+	 * will remain idle despite the ACTIVE flag being set.
+	 */
+	writel(BCM2835_DMA_INT | BCM2835_DMA_ACTIVE,
+	       c->chan_base + BCM2835_DMA_CS);
 
 	d = c->desc;
 
@@ -494,11 +506,7 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
 		if (d->cyclic) {
 			/* call the cyclic callback */
 			vchan_cyclic_callback(&d->vd);
-
-			/* Keep the DMA engine running */
-			writel(BCM2835_DMA_ACTIVE,
-			       c->chan_base + BCM2835_DMA_CS);
-		} else {
+		} else if (!readl(c->chan_base + BCM2835_DMA_ADDR)) {
 			vchan_cookie_complete(&c->desc->vd);
 			bcm2835_dma_start_desc(c);
 		}
@@ -806,11 +814,7 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
 	list_del_init(&c->node);
 	spin_unlock(&d->lock);
 
-	/*
-	 * Stop DMA activity: we assume the callback will not be called
-	 * after bcm_dma_abort() returns (even if it does, it will see
-	 * c->desc is NULL and exit.)
-	 */
+	/* stop DMA activity */
 	if (c->desc) {
 		vchan_terminate_vdesc(&c->desc->vd);
 		c->desc = NULL;
@@ -818,8 +822,7 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
 
 		/* Wait for stopping */
 		while (--timeout) {
-			if (!(readl(c->chan_base + BCM2835_DMA_CS) &
-						BCM2835_DMA_ACTIVE))
+			if (!readl(c->chan_base + BCM2835_DMA_ADDR))
 				break;
 
 			cpu_relax();