releases/5.11.3/serial-stm32-fix-dma-initialization-error-handling.patch

From cca89c154c2d9d37052401c8581ad0422ff38cf7 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Wed, 6 Jan 2021 17:21:56 +0100
Subject: serial: stm32: fix DMA initialization error handling

From: Erwan Le Ray <erwan.leray@foss.st.com>

[ Upstream commit e7997f7ff7f8154d477f6f976698d868a2ac3934 ]

DMA initialization error handling is not properly implemented in the
driver.
Fix DMA initialization error handling by:
- moving TX DMA descriptor request error handling in a new dedicated
fallback_err label
- adding error handling to TX DMA descriptor submission
- adding error handling to RX DMA descriptor submission

This patch depends on '24832ca3ee85 ("tty: serial: stm32-usart: Remove set
but unused 'cookie' variables")' which unfortunately doesn't include a
"Fixes" tag.

Fixes: 3489187204eb ("serial: stm32: adding dma support")
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Link: https://lore.kernel.org/r/20210106162203.28854-2-erwan.leray@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/stm32-usart.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index f4de32d3f2afe..6248304a001f4 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -383,17 +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 */
-	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);
@@ -402,6 +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)
@@ -1130,7 +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 */
-	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);
-- 
2.27.0