diff options
| author | Lars-Peter Clausen <lars@metafoo.de> | 2013-10-17 14:08:09 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-19 19:47:38 -0700 |
| commit | d3755f5e6cd222cd5aff949228d32aa8446023a5 (patch) | |
| tree | 56b68cd0b26533e32217333e5e0ff4cfa460ec63 | |
| parent | 85baf542d54ec321642194b0ebfa7316e3190dc2 (diff) | |
tty: xuartps: Force enable the UART in xuartps_console_write
It is possible that under certain circumstances xuartps_console_write is entered
while the UART disabled. When this happens the code will busy loop in
xuartps_console_putchar, since the character is never written and the TXEMPTY
flag is never set. The result is a system lockup. This patch force enables the
UART for the duration of xuartps_console_write to avoid this.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: John Linn <john.linn@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/serial/xilinx_uartps.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 6e8ec6e9d5a2..fdc739b55eb3 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -953,7 +953,7 @@ static void xuartps_console_write(struct console *co, const char *s, { struct uart_port *port = &xuartps_port[co->index]; unsigned long flags; - unsigned int imr; + unsigned int imr, ctrl; int locked = 1; if (oops_in_progress) @@ -965,9 +965,19 @@ static void xuartps_console_write(struct console *co, const char *s, imr = xuartps_readl(XUARTPS_IMR_OFFSET); xuartps_writel(imr, XUARTPS_IDR_OFFSET); + /* + * Make sure that the tx part is enabled. Set the TX enable bit and + * clear the TX disable bit to enable the transmitter. + */ + ctrl = xuartps_readl(XUARTPS_CR_OFFSET); + xuartps_writel((ctrl & ~XUARTPS_CR_TX_DIS) | XUARTPS_CR_TX_EN, + XUARTPS_CR_OFFSET); + uart_console_write(port, s, count, xuartps_console_putchar); xuartps_console_wait_tx(port); + xuartps_writel(ctrl, XUARTPS_CR_OFFSET); + /* restore interrupt state, it seems like there may be a h/w bug * in that the interrupt enable register should not need to be * written based on the data sheet |