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| author | Huang Shijie <b32955@freescale.com> | 2012-08-08 10:37:59 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-08-16 12:15:33 -0700 |
| commit | 00592021010ad86d3b26bac7034034f6af145a2c (patch) | |
| tree | ad64391844ab9a7cbfaf4a9b693ccd73586f75be /drivers/tty | |
| parent | 7d9739cd6b03575bc88c6ce3c60853dbc50a6ae2 (diff) | |
| download | linux-00592021010ad86d3b26bac7034034f6af145a2c.tar.bz2 | |
serial: mxs-auart: fix the wrong RTS hardware flow control
Without checking if the auart supports the hardware flow control or not,
the old mxs_auart_set_mctrl() asserted the RTS pin blindly.
This will causes the auart receives wrong data in the following case:
The far-end has already started the write operation, and wait for
the auart asserts the RTS pin. Then the auart starts the read operation,
but mxs_auart_set_mctrl() may be called before we set the RTSCTS in the
mxs_auart_settermios(). So the RTS pin is asserted in a wrong situation,
and we get the wrong data in the end.
This bug has been catched when I connect the mx23(DTE) to the mx53(DCE).
This patch also replaces the AUART_CTRL2_RTS with AUART_CTRL2_RTSEN.
We should use the real the hardware flow control, not the software-controled
hardware flow control.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/mxs-auart.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c index 2e341b81ff89..3a667eed63d6 100644 --- a/drivers/tty/serial/mxs-auart.c +++ b/drivers/tty/serial/mxs-auart.c @@ -73,6 +73,7 @@ #define AUART_CTRL0_CLKGATE (1 << 30) #define AUART_CTRL2_CTSEN (1 << 15) +#define AUART_CTRL2_RTSEN (1 << 14) #define AUART_CTRL2_RTS (1 << 11) #define AUART_CTRL2_RXE (1 << 9) #define AUART_CTRL2_TXE (1 << 8) @@ -259,9 +260,12 @@ static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl) u32 ctrl = readl(u->membase + AUART_CTRL2); - ctrl &= ~AUART_CTRL2_RTS; - if (mctrl & TIOCM_RTS) - ctrl |= AUART_CTRL2_RTS; + ctrl &= ~AUART_CTRL2_RTSEN; + if (mctrl & TIOCM_RTS) { + if (u->state->port.flags & ASYNC_CTS_FLOW) + ctrl |= AUART_CTRL2_RTSEN; + } + s->ctrl = mctrl; writel(ctrl, u->membase + AUART_CTRL2); } @@ -359,9 +363,9 @@ static void mxs_auart_settermios(struct uart_port *u, /* figure out the hardware flow control settings */ if (cflag & CRTSCTS) - ctrl2 |= AUART_CTRL2_CTSEN; + ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN; else - ctrl2 &= ~AUART_CTRL2_CTSEN; + ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN); /* set baud rate */ baud = uart_get_baud_rate(u, termios, old, 0, u->uartclk); |