Commit ee5e7c10 authored by Robin Gong's avatar Robin Gong Committed by Greg Kroah-Hartman

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: default avatarRobin Gong <b38343@freescale.com>
Signed-off-by: default avatarFugang Duan <B38611@freescale.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 068500e0
...@@ -946,8 +946,21 @@ static void dma_rx_callback(void *data) ...@@ -946,8 +946,21 @@ static void dma_rx_callback(void *data)
tty_flip_buffer_push(port); tty_flip_buffer_push(port);
start_rx_dma(sport); 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); imx_rx_dma_done(sport);
}
} }
static int start_rx_dma(struct imx_port *sport) static int start_rx_dma(struct imx_port *sport)
......
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