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authorHuang Shijie <b32955@freescale.com>2012-08-08 10:37:59 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-08-16 12:15:33 -0700
commit00592021010ad86d3b26bac7034034f6af145a2c (patch)
treead64391844ab9a7cbfaf4a9b693ccd73586f75be
parent7d9739cd6b03575bc88c6ce3c60853dbc50a6ae2 (diff)
downloadop-kernel-dev-00592021010ad86d3b26bac7034034f6af145a2c.zip
op-kernel-dev-00592021010ad86d3b26bac7034034f6af145a2c.tar.gz
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>
-rw-r--r--drivers/tty/serial/mxs-auart.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 2e341b8..3a667ee 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);
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