[PATCH v2 01/13] serial: stm32: fix probe and remove order for dma

[Erwan Le Ray]

The probe and remove orders are wrong as the uart_port is registered
before saving device data in the probe, and unregistered after DMA
resource deallocation in the remove. uart_port registering should be
done at the end of probe and unregistering should be done at the begin of
remove to avoid resource allocation issues.

Fix probe and remove orders. This enforce resource allocation occur at
proper time.
Terminate both DMA rx and tx transfers before removing device.

Move pm_runtime after uart_remove_one_port() call in remove() to keep the
probe error path.

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

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index b3675cf25a69..3d58824ac2af 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -1252,10 +1252,6 @@ static int stm32_usart_serial_probe(struct platform_device *pdev)
 		device_set_wakeup_enable(&pdev->dev, false);
 	}
 
-	ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
-	if (ret)
-		goto err_wirq;
-
 	ret = stm32_usart_of_dma_rx_probe(stm32port, pdev);
 	if (ret)
 		dev_info(&pdev->dev, "interrupt mode used for rx (no dma)\n");
@@ -1269,11 +1265,40 @@ static int stm32_usart_serial_probe(struct platform_device *pdev)
 	pm_runtime_get_noresume(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
+
+	ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
+	if (ret)
+		goto err_port;
+
 	pm_runtime_put_sync(&pdev->dev);
 
 	return 0;
 
-err_wirq:
+err_port:
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
+	if (stm32port->rx_ch) {
+		dmaengine_terminate_async(stm32port->rx_ch);
+		dma_release_channel(stm32port->rx_ch);
+	}
+
+	if (stm32port->rx_dma_buf)
+		dma_free_coherent(&pdev->dev,
+				  RX_BUF_L, stm32port->rx_buf,
+				  stm32port->rx_dma_buf);
+
+	if (stm32port->tx_ch) {
+		dmaengine_terminate_async(stm32port->tx_ch);
+		dma_release_channel(stm32port->tx_ch);
+	}
+
+	if (stm32port->tx_dma_buf)
+		dma_free_coherent(&pdev->dev,
+				  TX_BUF_L, stm32port->tx_buf,
+				  stm32port->tx_dma_buf);
+
 	if (stm32port->wakeirq > 0)
 		dev_pm_clear_wake_irq(&pdev->dev);
 
@@ -1295,11 +1320,20 @@ static int stm32_usart_serial_remove(struct platform_device *pdev)
 	int err;
 
 	pm_runtime_get_sync(&pdev->dev);
+	err = uart_remove_one_port(&stm32_usart_driver, port);
+	if (err)
+		return(err);
+
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
 
 	stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
 
-	if (stm32_port->rx_ch)
+	if (stm32_port->rx_ch) {
+		dmaengine_terminate_async(stm32_port->rx_ch);
 		dma_release_channel(stm32_port->rx_ch);
+	}
 
 	if (stm32_port->rx_dma_buf)
 		dma_free_coherent(&pdev->dev,
@@ -1308,8 +1342,10 @@ static int stm32_usart_serial_remove(struct platform_device *pdev)
 
 	stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
 
-	if (stm32_port->tx_ch)
+	if (stm32_port->tx_ch) {
+		dmaengine_terminate_async(stm32_port->tx_ch);
 		dma_release_channel(stm32_port->tx_ch);
+	}
 
 	if (stm32_port->tx_dma_buf)
 		dma_free_coherent(&pdev->dev,
@@ -1323,12 +1359,7 @@ static int stm32_usart_serial_remove(struct platform_device *pdev)
 
 	stm32_usart_deinit_port(stm32_port);
 
-	err = uart_remove_one_port(&stm32_usart_driver, port);
-
-	pm_runtime_disable(&pdev->dev);
-	pm_runtime_put_noidle(&pdev->dev);
-
-	return err;
+	return 0;
 }
 
 #ifdef CONFIG_SERIAL_STM32_CONSOLE
-- 
2.17.1