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[PATCH v3 6/6] serial: imx: Fix imx_shutdown procedure

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From: Nandor Han <nandor.han@ge.com>

In some cases, it looks that interrupts can happen after the dma was
disabled and port was not yet shutdown. This will result in interrupts
handled by imx_rxint.

This commits updates the shutdown function to ensure that underlying
components are disabled in the right order. This disables RX and TX
blocks, then it disabled interrupts. In case DMA is enabled, it disables
DMA and free corresponding resources. It disables UART port and stop
clocks.

Signed-off-by: Nandor Han <nandor.han@ge.com>
Signed-off-by: Romain Perier <romain.perier@collabora.com>
Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
---
 drivers/tty/serial/imx.c | 34 +++++++++++++++-------------------
 1 file changed, 15 insertions(+), 19 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 256b128..393c1c0 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1368,44 +1368,40 @@ static void imx_shutdown(struct uart_port *port)
 	unsigned long temp;
 	unsigned long flags;
 
-	if (sport->dma_is_enabled) {
-		sport->dma_is_rxing = 0;
-		sport->dma_is_txing = 0;
-		dmaengine_terminate_sync(sport->dma_chan_tx);
-		dmaengine_terminate_sync(sport->dma_chan_rx);
-
+	if (!sport->port.suspended) {
 		spin_lock_irqsave(&sport->port.lock, flags);
 		imx_stop_tx(port);
 		imx_stop_rx(port);
-		imx_disable_dma(sport);
+
+		if (sport->dma_is_inited && sport->dma_is_enabled)
+			imx_disable_dma(sport);
+
 		spin_unlock_irqrestore(&sport->port.lock, flags);
 		imx_uart_dma_exit(sport);
 	}
 
-	mctrl_gpio_disable_ms(sport->gpios);
-
 	spin_lock_irqsave(&sport->port.lock, flags);
 	temp = readl(sport->port.membase + UCR2);
-	temp &= ~(UCR2_TXEN);
+	temp &= ~(UCR2_TXEN | UCR2_RXEN);
 	writel(temp, sport->port.membase + UCR2);
+	temp = readl(sport->port.membase + UCR4);
+	temp &= ~UCR4_OREN;
+	writel(temp, sport->port.membase + UCR4);
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 
-	/*
-	 * Stop our timer.
-	 */
-	del_timer_sync(&sport->timer);
+	mctrl_gpio_disable_ms(sport->gpios);
 
-	/*
-	 * Disable all interrupts, port and break condition.
-	 */
+	/* Stop our timer. */
+	del_timer_sync(&sport->timer);
 
+	/* Disable port. */
 	spin_lock_irqsave(&sport->port.lock, flags);
 	temp = readl(sport->port.membase + UCR1);
-	temp &= ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN);
-
+	temp &= ~UCR1_UARTEN;
 	writel(temp, sport->port.membase + UCR1);
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 
+	/* Disable clocks. */
 	clk_disable_unprepare(sport->clk_per);
 	clk_disable_unprepare(sport->clk_ipg);
 }
-- 
1.8.3.1

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[PATCH v3 0/6] serial: imx: various improvements Martyn Welch <martyn.welch@collabora.co.uk> - 2017-09-21 18:20 +0200
  [PATCH v3 3/6] serial: imx: Simplify DMA disablement Martyn Welch <martyn.welch@collabora.co.uk> - 2017-09-21 18:20 +0200
  [PATCH v3 6/6] serial: imx: Fix imx_shutdown procedure Martyn Welch <martyn.welch@collabora.co.uk> - 2017-09-21 18:20 +0200
  [PATCH v3 4/6] serial: imx: unmap sg buffers when DMA channel is released Martyn Welch <martyn.welch@collabora.co.uk> - 2017-09-21 18:20 +0200
    Re: [PATCH v3 4/6] serial: imx: unmap sg buffers when DMA channel is  released Uwe Kleine-König          <u.kleine-koenig@pengutronix.de> - 2017-09-21 20:30 +0200
  [PATCH v3 1/6] serial: imx: remove CTSC and CTS handling from imx_disable_dma Martyn Welch <martyn.welch@collabora.co.uk> - 2017-09-21 18:30 +0200
    Re: [PATCH v3 1/6] serial: imx: remove CTSC and CTS handling from  imx_disable_dma Uwe Kleine-König          <u.kleine-koenig@pengutronix.de> - 2017-09-21 20:30 +0200
      Re: [PATCH v3 1/6] serial: imx: remove CTSC and CTS handling from  imx_disable_dma Martyn Welch <martyn.welch@collabora.co.uk> - 2017-09-21 21:20 +0200

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