dmaengine: virt-dma: Add helper to free/reuse a descriptor

The vchan_vdesc_fini() can be used to free or reuse a given descriptor
after it has been marked as completed.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/virt-dma.c

@@ -107,10 +107,7 @@ static void vchan_complete(unsigned long arg)
 		dmaengine_desc_get_callback(&vd->tx, &cb);
 
 		list_del(&vd->node);
-		if (dmaengine_desc_test_reuse(&vd->tx))
-			list_add(&vd->node, &vc->desc_allocated);
-		else
-			vc->desc_free(vd);
+		vchan_vdesc_fini(vd);
 
 		dmaengine_desc_callback_invoke(&cb, NULL);
 	}

drivers/dma/virt-dma.h

@@ -103,6 +103,20 @@ static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
 	tasklet_schedule(&vc->task);
 }
 
+/**
+ * vchan_vdesc_fini - Free or reuse a descriptor
+ * @vd: virtual descriptor to free/reuse
+ */
+static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
+{
+	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
+
+	if (dmaengine_desc_test_reuse(&vd->tx))
+		list_add(&vd->node, &vc->desc_allocated);
+	else
+		vc->desc_free(vd);
+}
+
 /**
  * vchan_cyclic_callback - report the completion of a period
  * @vd: virtual descriptor