diff options
| author | Robin Gong <b38343@freescale.com> | 2014-12-09 18:11:33 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-01-09 14:23:59 -0800 |
| commit | ee5e7c1091a703c6a465d8145e9b55e09adb6f37 (patch) | |
| tree | 2ead6ca7b06150c1f04e7944729f591df6b654da /drivers/tty/serial/imx.c | |
| parent | 068500e08dc87ea9a453cc4a500cf3ab28d0f936 (diff) | |
serial: imx: start rx_dma once RXFIFO is not empty
Start rx_dma once RXFIFO is not empty that can avoid dma request lost
and causes data delay issue.
Signed-off-by: Robin Gong <b38343@freescale.com>
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/imx.c')
| -rw-r--r-- | drivers/tty/serial/imx.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index ab958a59cae9..d61b89e4a96e 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -946,8 +946,21 @@ static void dma_rx_callback(void *data) tty_flip_buffer_push(port); start_rx_dma(sport); - } else + } else if (readl(sport->port.membase + USR2) & USR2_RDR) { + /* + * start rx_dma directly once data in RXFIFO, more efficient + * than before: + * 1. call imx_rx_dma_done to stop dma if no data received + * 2. wait next RDR interrupt to start dma transfer. + */ + start_rx_dma(sport); + } else { + /* + * stop dma to prevent too many IDLE event trigged if no data + * in RXFIFO + */ imx_rx_dma_done(sport); + } } static int start_rx_dma(struct imx_port *sport) |