dmaengine: mxs: Drop unnecessary flag

The mxs dma driver insists on having the DMA_PREP_INTERRUPT flag set
on all but the first transfer. There's no need to let the user set this
flag, the driver can do it internally whenever it needs it. Drop
handling of this flag from the driver.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/dma/mxs-dma.c

@@ -477,16 +477,16 @@ static void mxs_dma_free_chan_resources(struct dma_chan *chan)
  *            ......
  *            ->device_prep_slave_sg(0);
  *            ......
- *            ->device_prep_slave_sg(DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ *            ->device_prep_slave_sg(DMA_CTRL_ACK);
  *            ......
  *    [3] If there are more than two DMA commands in the DMA chain, the code
  *        should be:
  *            ......
  *            ->device_prep_slave_sg(0);                                // First
  *            ......
- *            ->device_prep_slave_sg(DMA_PREP_INTERRUPT [| DMA_CTRL_ACK]);
+ *            ->device_prep_slave_sg(DMA_CTRL_ACK]);
  *            ......
- *            ->device_prep_slave_sg(DMA_PREP_INTERRUPT | DMA_CTRL_ACK); // Last
+ *            ->device_prep_slave_sg(DMA_CTRL_ACK); // Last
  *            ......
  */
 static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
@@ -500,13 +500,12 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
 	struct scatterlist *sg;
 	u32 i, j;
 	u32 *pio;
-	bool append = flags & DMA_PREP_INTERRUPT;
-	int idx = append ? mxs_chan->desc_count : 0;
+	int idx = 0;
 
-	if (mxs_chan->status == DMA_IN_PROGRESS && !append)
-		return NULL;
+	if (mxs_chan->status == DMA_IN_PROGRESS)
+		idx = mxs_chan->desc_count;
 
-	if (sg_len + (append ? idx : 0) > NUM_CCW) {
+	if (sg_len + idx > NUM_CCW) {
 		dev_err(mxs_dma->dma_device.dev,
 				"maximum number of sg exceeded: %d > %d\n",
 				sg_len, NUM_CCW);
@@ -520,7 +519,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
 	 * If the sg is prepared with append flag set, the sg
 	 * will be appended to the last prepared sg.
 	 */
-	if (append) {
+	if (idx) {
 		BUG_ON(idx < 1);
 		ccw = &mxs_chan->ccw[idx - 1];
 		ccw->next = mxs_chan->ccw_phys + sizeof(*ccw) * idx;