| Message ID | 1381487461-12850-3-git-send-email-b32955@freescale.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 708ba89..c6c3b16 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -795,8 +795,15 @@ static irqreturn_t imx_int(int irq, void *dev_id) static unsigned int imx_tx_empty(struct uart_port *port) { struct imx_port *sport = (struct imx_port *)port; + unsigned int ret; - return (readl(sport->port.membase + USR2) & USR2_TXDC) ? TIOCSER_TEMT : 0; + ret = (readl(sport->port.membase + USR2) & USR2_TXDC) ? TIOCSER_TEMT : 0; + + /* If the TX DMA is working, return 0. */ + if (sport->dma_is_enabled && sport->dma_is_txing) + ret = 0; + + return ret; } /*
Assume the following situation: If the DMA is enabled, and the a TX DMA operation is working, But we have not issued the TX DMA operation (or we have issued the TX DMA operation with dma_async_issue_pending(), but the DMA has not started to move the data from the memory to the TXFIFO). At this time, we may get the wrong status of the transmitter when we call the imx_tx_empty. In such situation, only check the USR2_TXDC does not enough for us. This patch checks the DMA's situation, and return 0 when the TX DMA is working. Signed-off-by: Huang Shijie <b32955@freescale.com> --- drivers/tty/serial/imx.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)