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serial: imx: Avoid post-PIO cleanup if TX DMA is started

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The imx_transmit_buffer function should return if TX DMA has already
been started and not just skip over the buffer PIO write loop. (Which
did fix the initial problem, but could have unintentional side-effects)

Tested on an i.MX6Q board with half-duplex RS-485 and with RS-232.

Cc: Clemens Gruber <clemens.gruber@pqgruber.com>
Cc: Uwe-Kleine König <u.kleine-koenig@pengutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Fixes: 514ab34dba ("serial: imx: Prevent TX buffer PIO write when a DMA has been started")
Signed-off-by: Ian Jamison <ian.dev@arkver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Jamison 2017-08-28 09:02:29 +01:00 committed by Greg Kroah-Hartman
parent 81b289cc14
commit 5aabd3b007
1 changed files with 4 additions and 1 deletions
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5
drivers/tty/serial/imx.c
View file

@ -457,7 +457,10 @@ static inline void imx_transmit_buffer(struct imx_port *sport)
}
}
while (!uart_circ_empty(xmit) && !sport->dma_is_txing &&
if (sport->dma_is_txing)
return;
while (!uart_circ_empty(xmit) &&
!(readl(sport->port.membase + uts_reg(sport)) & UTS_TXFULL)) {
/* send xmit->buf[xmit->tail]
* out the port here */