diff options
| author | Robin Gong <b38343@freescale.com> | 2014-07-11 17:47:17 +0800 |
|---|---|---|
| committer | Nitin Garg <nitin.garg@freescale.com> | 2015-09-17 08:58:25 -0500 |
| commit | cf053edbdfed006ec393c739f99b7a8bec6e47fb (patch) | |
| tree | 7eeb3f8deb2edd77353a60b74076f3183a19d721 /drivers/tty | |
| parent | e385aa924fca75ebe59ca6e16fa4e1161e049eca (diff) | |
ENGR00322581-03 tty: 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.
(cherry picked from commit 9271c626e207f9a4578b4696e520253a3bd0ad32)
Signed-off-by: Robin Gong <b38343@freescale.com>
Signed-off-by: Fugang Duan <B38611@freescale.com>
Diffstat (limited to 'drivers/tty')
| -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 f43c0e32c4f0..d91a5cfdac6f 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -943,8 +943,21 @@ 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) |