[PATCH 1/8] serial: stm32: fix -Wall W=1 compilation warnings

[Erwan Le Ray <erwan.leray@xxxxxxxxxxx>]

Fix compilations warning detected by -Wall W=1 compilation option:
- warning: variable ‘cookie’ set but not used

Fixes: 3489187204eb ("serial: stm32: adding dma support")
Signed-off-by: Erwan Le Ray <erwan.leray@xxxxxxxxxxx>

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index ee6c7762d355..6248304a001f 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -350,7 +350,6 @@ static void stm32_transmit_chars_dma(struct uart_port *port)
 	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
 	struct circ_buf *xmit = &port->state->xmit;
 	struct dma_async_tx_descriptor *desc = NULL;
-	dma_cookie_t cookie;
 	unsigned int count, i;
 
 	if (stm32port->tx_dma_busy)
@@ -384,17 +383,18 @@ static void stm32_transmit_chars_dma(struct uart_port *port)
 					   DMA_MEM_TO_DEV,
 					   DMA_PREP_INTERRUPT);
 
-	if (!desc) {
-		for (i = count; i > 0; i--)
-			stm32_transmit_chars_pio(port);
-		return;
-	}
+	if (!desc)
+		goto fallback_err;
 
 	desc->callback = stm32_tx_dma_complete;
 	desc->callback_param = port;
 
 	/* Push current DMA TX transaction in the pending queue */
-	cookie = dmaengine_submit(desc);
+	if (dma_submit_error(dmaengine_submit(desc))) {
+		/* dma no yet started, safe to free resources */
+		dmaengine_terminate_async(stm32port->tx_ch);
+		goto fallback_err;
+	}
 
 	/* Issue pending DMA TX requests */
 	dma_async_issue_pending(stm32port->tx_ch);
@@ -403,6 +403,11 @@ static void stm32_transmit_chars_dma(struct uart_port *port)
 
 	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
 	port->icount.tx += count;
+	return;
+
+fallback_err:
+	for (i = count; i > 0; i--)
+		stm32_transmit_chars_pio(port);
 }
 
 static void stm32_transmit_chars(struct uart_port *port)
@@ -1087,7 +1092,6 @@ static int stm32_of_dma_rx_probe(struct stm32_port *stm32port,
 	struct device *dev = &pdev->dev;
 	struct dma_slave_config config;
 	struct dma_async_tx_descriptor *desc = NULL;
-	dma_cookie_t cookie;
 	int ret;
 
 	/* Request DMA RX channel */
@@ -1132,7 +1136,11 @@ static int stm32_of_dma_rx_probe(struct stm32_port *stm32port,
 	desc->callback_param = NULL;
 
 	/* Push current DMA transaction in the pending queue */
-	cookie = dmaengine_submit(desc);
+	ret = dma_submit_error(dmaengine_submit(desc));
+	if (ret) {
+		dmaengine_terminate_sync(stm32port->rx_ch);
+		goto config_err;
+	}
 
 	/* Issue pending DMA requests */
 	dma_async_issue_pending(stm32port->rx_ch);
-- 
2.17.1