spi: dw-dma: Check DMA Tx-desc submission status

We suggest to add the dmaengine_submit() return value test for errors.  It
has been unnecessary while the driver was expected to be utilized in pair
with DW DMAC. But since now the driver can be used with any DMA engine, it
might be useful to track the errors on DMA submissions so not miss them
and get into an unpredictable driver behaviour.
Signed-off-by: NSerge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200920112322.24585-7-Sergey.Semin@baikalelectronics.ruSigned-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-dw-dma.c

@@ -275,6 +275,8 @@ static struct dma_async_tx_descriptor *
 dw_spi_dma_submit_tx(struct dw_spi *dws, struct spi_transfer *xfer)
 {
 	struct dma_async_tx_descriptor *txdesc;
+	dma_cookie_t cookie;
+	int ret;
 
 	txdesc = dmaengine_prep_slave_sg(dws->txchan,
 				xfer->tx_sg.sgl,
@@ -287,7 +289,13 @@ dw_spi_dma_submit_tx(struct dw_spi *dws, struct spi_transfer *xfer)
 	txdesc->callback = dw_spi_dma_tx_done;
 	txdesc->callback_param = dws;
 
-	dmaengine_submit(txdesc);
+	cookie = dmaengine_submit(txdesc);
+	ret = dma_submit_error(cookie);
+	if (ret) {
+		dmaengine_terminate_sync(dws->txchan);
+		return NULL;
+	}
+
 	set_bit(TX_BUSY, &dws->dma_chan_busy);
 
 	return txdesc;
@@ -371,6 +379,8 @@ static struct dma_async_tx_descriptor *dw_spi_dma_submit_rx(struct dw_spi *dws,
 		struct spi_transfer *xfer)
 {
 	struct dma_async_tx_descriptor *rxdesc;
+	dma_cookie_t cookie;
+	int ret;
 
 	rxdesc = dmaengine_prep_slave_sg(dws->rxchan,
 				xfer->rx_sg.sgl,
@@ -383,7 +393,13 @@ static struct dma_async_tx_descriptor *dw_spi_dma_submit_rx(struct dw_spi *dws,
 	rxdesc->callback = dw_spi_dma_rx_done;
 	rxdesc->callback_param = dws;
 
-	dmaengine_submit(rxdesc);
+	cookie = dmaengine_submit(rxdesc);
+	ret = dma_submit_error(cookie);
+	if (ret) {
+		dmaengine_terminate_sync(dws->rxchan);
+		return NULL;
+	}
+
 	set_bit(RX_BUSY, &dws->dma_chan_busy);
 
 	return rxdesc;