cyclic code diff to upstream+dmapool patch

cyclic-upstream.diff

index 996c4b0..773b23e9 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -358,9 +376,18 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 	struct bcm2835_desc *d;
 	dma_addr_t dev_addr;
 	unsigned int es, sync_type;
-	unsigned int frame;
+	unsigned int frame, max_size;
 	int i;
 
+	if (!buf_len || !period_len)
+		return NULL;
+
+	if (buf_len % period_len) {
+		dev_err(chan->device->dev,
+			 "Buffer length should be a multiple of period\n");
+		return NULL;
+	}
+
 	/* Grab configuration */
 	if (!is_slave_direction(direction)) {
 		dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
@@ -386,6 +413,18 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 		return NULL;
 	}
 
+	if (c->ch >= 8) /* LITE channel */
+		max_size = MAX_LITE_TRANSFER;
+	else
+		max_size = MAX_NORMAL_TRANSFER;
+
+	if (period_len > max_size) {
+		dev_err(chan->device->dev,
+			"Period length %d larger than maximum %d\n",
+			period_len, max_size);
+		return NULL;
+	}
+
 	/* Now allocate and setup the descriptor. */
 	d = kzalloc(sizeof(*d), GFP_NOWAIT);
 	if (!d)
@@ -446,12 +485,14 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 
 		/*
 		 * Next block is the next frame.
-		 * This DMA engine driver currently only supports cyclic DMA.
+		 * This function is called on cyclic DMA transfers.
 		 * Therefore, wrap around at number of frames.
 		 */
 		control_block->next = d->cb_list[((frame + 1) % d->frames)].paddr;
 	}
 
+	c->cyclic = true;
+
 	return vchan_tx_prep(&c->vc, &d->vd, flags);
 error_cb:
 	i--;