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

drivers/tty/serial/imx.c

+14 −1
Original line number Diff line number Diff line
@@ -946,9 +946,22 @@ 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)

{