dma: pl330: split off common code to give back descriptors

This patch adds __pl330_giveback_descs which give back descriptors when fails
allocating descriptors. It requires to eliminate duplication for
pl330_prep_dma_sg which will be added later.

Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Acked-by : Jassi Brar <jassisinghbrar@gmail.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/pl330.c

@@ -2814,6 +2814,28 @@ pl330_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dst,
 	return &desc->txd;
 }
 
+static void __pl330_giveback_desc(struct dma_pl330_dmac *pdmac,
+				  struct dma_pl330_desc *first)
+{
+	unsigned long flags;
+	struct dma_pl330_desc *desc;
+
+	if (!first)
+		return;
+
+	spin_lock_irqsave(&pdmac->pool_lock, flags);
+
+	while (!list_empty(&first->node)) {
+		desc = list_entry(first->node.next,
+				struct dma_pl330_desc, node);
+		list_move_tail(&desc->node, &pdmac->desc_pool);
+	}
+
+	list_move_tail(&first->node, &pdmac->desc_pool);
+
+	spin_unlock_irqrestore(&pdmac->pool_lock, flags);
+}
+
 static struct dma_async_tx_descriptor *
 pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 		unsigned int sg_len, enum dma_transfer_direction direction,
@@ -2822,7 +2844,6 @@ pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	struct dma_pl330_desc *first, *desc = NULL;
 	struct dma_pl330_chan *pch = to_pchan(chan);
 	struct scatterlist *sg;
-	unsigned long flags;
 	int i;
 	dma_addr_t addr;
 
@@ -2842,20 +2863,7 @@ pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 			dev_err(pch->dmac->pif.dev,
 				"%s:%d Unable to fetch desc\n",
 				__func__, __LINE__);
-			if (!first)
-				return NULL;
-
-			spin_lock_irqsave(&pdmac->pool_lock, flags);
-
-			while (!list_empty(&first->node)) {
-				desc = list_entry(first->node.next,
-						struct dma_pl330_desc, node);
-				list_move_tail(&desc->node, &pdmac->desc_pool);
-			}
-
-			list_move_tail(&first->node, &pdmac->desc_pool);
-
-			spin_unlock_irqrestore(&pdmac->pool_lock, flags);
+			__pl330_giveback_desc(pdmac, first);
 
 			return NULL;
 		}