dmaengine: virt-dma: store result on dma descriptor

This allows each virtual channel to store information about each transfer
that completed, i.e. which transfer succeeded (or which failed) and if
there was any residue data on each (completed) transfer.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/virt-dma.c

@@ -101,7 +101,7 @@ static void vchan_complete(unsigned long arg)
 	}
 	spin_unlock_irq(&vc->lock);
 
-	dmaengine_desc_callback_invoke(&cb, NULL);
+	dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
 
 	list_for_each_entry_safe(vd, _vd, &head, node) {
 		dmaengine_desc_get_callback(&vd->tx, &cb);
@@ -109,7 +109,7 @@ static void vchan_complete(unsigned long arg)
 		list_del(&vd->node);
 		vchan_vdesc_fini(vd);
 
-		dmaengine_desc_callback_invoke(&cb, NULL);
+		dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
 	}
 }
 

drivers/dma/virt-dma.h

@@ -17,6 +17,7 @@
 
 struct virt_dma_desc {
 	struct dma_async_tx_descriptor tx;
+	struct dmaengine_result tx_result;
 	/* protected by vc.lock */
 	struct list_head node;
 };
@@ -65,6 +66,9 @@ static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan
 	vd->tx.tx_submit = vchan_tx_submit;
 	vd->tx.desc_free = vchan_tx_desc_free;
 
+	vd->tx_result.result = DMA_TRANS_NOERROR;
+	vd->tx_result.residue = 0;
+
 	spin_lock_irqsave(&vc->lock, flags);
 	list_add_tail(&vd->node, &vc->desc_allocated);
 	spin_unlock_irqrestore(&vc->lock, flags);