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Commit e2f27866 authored by Huang Shijie's avatar Huang Shijie Committed by Greg Kroah-Hartman
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serial: imx: remove the DMA wait queue 



The DMA wait queue makes the code very complicated:
  For RX, the @->stop_rx hook does not really stop the RX;
  For TX, the @->stop_tx hook does not really stop the TX.

The above make the imx_shutdown has to wait the RX/TX DMA to be finished.

In order to make code more simple, this patch removes the DMA wait queue.
By calling the dmaengine_terminate_all, this patch makes the RX stops
immediately after we call the @->stop_rx hook, so does the TX.

Signed-off-by: default avatarHuang Shijie <b32955@freescale.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8eccd0cd

drivers/tty/serial/imx.c

+14 −28
Original line number Diff line number Diff line
@@ -225,7 +225,6 @@ struct imx_port { 
	void			*rx_buf;

	unsigned int		tx_bytes;

	unsigned int		dma_tx_nents;

	wait_queue_head_t	dma_wait;

};



struct imx_port_ucrs {
@@ -416,12 +415,10 @@ static void imx_stop_tx(struct uart_port *port) 
		return;

	}



	/*

	 * We are maybe in the SMP context, so if the DMA TX thread is running

	 * on other cpu, we have to wait for it to finish.

	 */

	if (sport->dma_is_enabled && sport->dma_is_txing)

		return;

	if (sport->dma_is_enabled && sport->dma_is_txing) {

		dmaengine_terminate_all(sport->dma_chan_tx);

		sport->dma_is_txing = 0;

	}



	temp = readl(sport->port.membase + UCR1);

	writel(temp & ~UCR1_TXMPTYEN, sport->port.membase + UCR1);
@@ -435,12 +432,10 @@ static void imx_stop_rx(struct uart_port *port) 
	struct imx_port *sport = (struct imx_port *)port;

	unsigned long temp;



	/*

	 * We are maybe in the SMP context, so if the DMA TX thread is running

	 * on other cpu, we have to wait for it to finish.

	 */

	if (sport->dma_is_enabled && sport->dma_is_rxing)

		return;

	if (sport->dma_is_enabled && sport->dma_is_rxing) {

		dmaengine_terminate_all(sport->dma_chan_rx);

		sport->dma_is_rxing = 0;

	}



	temp = readl(sport->port.membase + UCR2);

	writel(temp & ~UCR2_RXEN, sport->port.membase + UCR2);
@@ -497,12 +492,6 @@ static void dma_tx_callback(void *data) 
	dev_dbg(sport->port.dev, "we finish the TX DMA.\n");



	uart_write_wakeup(&sport->port);



	if (waitqueue_active(&sport->dma_wait)) {

		wake_up(&sport->dma_wait);

		dev_dbg(sport->port.dev, "exit in %s.\n", __func__);

		return;

	}

}



static void imx_dma_tx(struct imx_port *sport)
@@ -875,10 +864,6 @@ static void imx_rx_dma_done(struct imx_port *sport) 
	writel(temp, sport->port.membase + UCR1);



	sport->dma_is_rxing = 0;



	/* Is the shutdown waiting for us? */

	if (waitqueue_active(&sport->dma_wait))

		wake_up(&sport->dma_wait);

}



/*
@@ -1025,8 +1010,6 @@ static void imx_enable_dma(struct imx_port *sport) 
{

	unsigned long temp;



	init_waitqueue_head(&sport->dma_wait);



	/* set UCR1 */

	temp = readl(sport->port.membase + UCR1);

	temp |= UCR1_RDMAEN | UCR1_TDMAEN | UCR1_ATDMAEN |
@@ -1218,10 +1201,13 @@ static void imx_shutdown(struct uart_port *port) 
	unsigned long flags;



	if (sport->dma_is_enabled) {

		/* We have to wait for the DMA to finish. */

		wait_event(sport->dma_wait,

			!sport->dma_is_rxing && !sport->dma_is_txing);

		/*

		 * The upper layer may does not call the @->stop_tx and

		 * @->stop_rx, so we call them ourselves.

		 */

		imx_stop_tx(port);

		imx_stop_rx(port);



		imx_disable_dma(sport);

		imx_uart_dma_exit(sport);

	}