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: Huang Shijie <b32955@xxxxxxxxxxxxx>
---
rebase this patch on the linux-next.
---
drivers/tty/serial/imx.c | 42 ++++++++++++++----------------------------
1 files changed, 14 insertions(+), 28 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index febf400..366f169 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -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);
}
--
1.7.8
--
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