linux-kernel - [PATCH 1/4] serial: stm32: move tx dma terminate DMA to shutdown

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Message-ID: <20220104182445.4195-2-valentin.caron@foss.st.com>
Date:   Tue, 4 Jan 2022 19:24:42 +0100
From:   Valentin Caron <valentin.caron@...s.st.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Jiri Slaby <jirislaby@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Gerald Baeza <gerald.baeza@...com>,
        Erwan Le Ray <erwan.leray@...s.st.com>,
        Valentin Caron <valentin.caron@...s.st.com>,
        <linux-serial@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/4] serial: stm32: move tx dma terminate DMA to shutdown

Terminate DMA transaction and clear CR3_DMAT when shutdown is requested,
instead of when remove is requested. If DMA transfer is not stopped in
shutdown ops, driver will fail to start a new DMA transfer after next
startup ops.

Fixes: 3489187204eb ("serial: stm32: adding dma support")

Signed-off-by: Erwan Le Ray <erwan.leray@...s.st.com>
Signed-off-by: Valentin Caron <valentin.caron@...s.st.com>
---
 drivers/tty/serial/stm32-usart.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 3244e7f6818c..6cfc3bec6749 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -883,6 +883,11 @@ static void stm32_usart_shutdown(struct uart_port *port)
 	u32 val, isr;
 	int ret;
 
+	if (stm32_port->tx_dma_busy) {
+		dmaengine_terminate_async(stm32_port->tx_ch);
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+	}
+
 	/* Disable modem control interrupts */
 	stm32_usart_disable_ms(port);
 
@@ -1570,7 +1575,6 @@ static int stm32_usart_serial_remove(struct platform_device *pdev)
 	writel_relaxed(cr3, port->membase + ofs->cr3);
 
 	if (stm32_port->tx_ch) {
-		dmaengine_terminate_async(stm32_port->tx_ch);
 		stm32_usart_of_dma_tx_remove(stm32_port, pdev);
 		dma_release_channel(stm32_port->tx_ch);
 	}
-- 
2.17.1