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| author | Fabio Estevam <fabio.estevam@freescale.com> | 2015-01-13 15:00:26 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-02-02 21:11:24 +0300 |
| commit | 934084a9d2d95d0ce98ae8d1ec3bfe81c95c678c (patch) | |
| tree | ca28c2c469b8d9f7091f89c1575de278de24e3dc /drivers/tty/serial/imx.c | |
| parent | bfc2e07f910891516c8eeef61859fa17369fea9f (diff) | |
| download | linux-934084a9d2d95d0ce98ae8d1ec3bfe81c95c678c.tar.xz | |
serial: imx: Fix imx_flush_buffer()
When running an userspace program that does a 'tcflush(fd, TCIOFLUSH)' call
we still see the last received character in the URXD register afterwards.
Clear UCR2_SRST bit so that the UART FIFO is flushed properly.
Since UCR2_SRST also resets some UART registers, we need to save and restore
some of them.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Tested-by: Fugang Duan <B38611@freescale.com>
Acked-by: Jason Liu <r64343@freecale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/imx.c')
| -rw-r--r-- | drivers/tty/serial/imx.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 59d9ef10b085..0eb29b1c47ac 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1320,6 +1320,7 @@ static void imx_flush_buffer(struct uart_port *port) struct imx_port *sport = (struct imx_port *)port; struct scatterlist *sgl = &sport->tx_sgl[0]; unsigned long temp; + int i = 100, ubir, ubmr, ubrc, uts; if (!sport->dma_chan_tx) return; @@ -1334,6 +1335,31 @@ static void imx_flush_buffer(struct uart_port *port) writel(temp, sport->port.membase + UCR1); sport->dma_is_txing = false; } + + /* + * According to the Reference Manual description of the UART SRST bit: + * "Reset the transmit and receive state machines, + * all FIFOs and register USR1, USR2, UBIR, UBMR, UBRC, URXD, UTXD + * and UTS[6-3]". As we don't need to restore the old values from + * USR1, USR2, URXD, UTXD, only save/restore the other four registers + */ + ubir = readl(sport->port.membase + UBIR); + ubmr = readl(sport->port.membase + UBMR); + ubrc = readl(sport->port.membase + UBRC); + uts = readl(sport->port.membase + IMX21_UTS); + + temp = readl(sport->port.membase + UCR2); + temp &= ~UCR2_SRST; + writel(temp, sport->port.membase + UCR2); + + while (!(readl(sport->port.membase + UCR2) & UCR2_SRST) && (--i > 0)) + udelay(1); + + /* Restore the registers */ + writel(ubir, sport->port.membase + UBIR); + writel(ubmr, sport->port.membase + UBMR); + writel(ubrc, sport->port.membase + UBRC); + writel(uts, sport->port.membase + IMX21_UTS); } static void |