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authorIan Jamison <ian.dev@arkver.com>2017-07-14 17:31:57 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-07-17 14:14:24 +0200
commit514ab34dbad6c6fa824a1f56984c196e59082346 (patch)
tree5ed905cb91764957f980f0055dd95db111ea9488 /drivers/tty
parent351ea50df545a4acaf8f61784949ceedbe923f03 (diff)
downloadlinux-stericsson-514ab34dbad6c6fa824a1f56984c196e59082346.tar.gz
serial: imx: Prevent TX buffer PIO write when a DMA has been started
Function imx_transmit_buffer starts a TX DMA if DMA is enabled, since commit 91a1a909f921 ("serial: imx: Support sw flow control in DMA mode"). It also carries on and attempts to write the same TX buffer using PIO. This results in TX data corruption and double-incrementing xmit->tail with the knock-on effect of tail passing head and a page of garbage being sent out. This seems to be triggered mostly when using RS485 half duplex on SMP systems, but is probably not limited to just those. Tested locally on an i.MX6Q with an RS485 half duplex transceiver on UART3, and also by Clemens Gruber. Tested-by: Clemens Gruber <clemens.gruber@pqgruber.com> Signed-off-by: Ian Jamison <ian.dev@arkver.com> Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/imx.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index e33da75ceac5..80934e7bd67f 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -458,7 +458,7 @@ static inline void imx_transmit_buffer(struct imx_port *sport)
}
}
- while (!uart_circ_empty(xmit) &&
+ while (!uart_circ_empty(xmit) && !sport->dma_is_txing &&
!(readl(sport->port.membase + uts_reg(sport)) & UTS_TXFULL)) {
/* send xmit->buf[xmit->tail]
* out the port here */