serial: mxc: have putc use the TXFIFO

only waiting for TXEMPTY leads to corrupted messages going over the
wire - which is fixed by making use of the FIFO

this change is following the linux kernel uart driver
(drivers/tty/serial/imx.c), which also checks UTS_TXFULL
instead of UTS_TXEMPTY

Signed-off-by: Johannes Schneider <johannes.schneider@leica-geosystems.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>

diff --git a/drivers/serial/serial_mxc.c b/drivers/serial/serial_mxc.c
index ee17a96..af1fd1e 100644 (file)
--- a/drivers/serial/serial_mxc.c
+++ b/drivers/serial/serial_mxc.c
@@ -311,7 +311,7 @@ static int mxc_serial_putc(struct udevice *dev, const char ch)
        struct mxc_serial_plat *plat = dev_get_plat(dev);
        struct mxc_uart *const uart = plat->reg;
 
-       if (!(readl(&uart->ts) & UTS_TXEMPTY))
+       if (readl(&uart->ts) & UTS_TXFULL)
                return -EAGAIN;
 
        writel(ch, &uart->txd);