diff options
| -rw-r--r-- | drivers/tty/serial/8250/8250_dw.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index cd1b94a0f451..41618b780146 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -9,6 +9,7 @@ * LCR is written whilst busy. If it is, then a busy detect interrupt is * raised, the LCR needs to be rewritten and the uart status register read. */ +#include <linux/delay.h> #include <linux/device.h> #include <linux/io.h> #include <linux/module.h> @@ -119,10 +120,27 @@ static void dw8250_check_lcr(struct uart_port *p, int value) */ } +/* Returns once the transmitter is empty or we run out of retries */ +static void dw8250_tx_wait_empty(struct uart_port *p, int tries) +{ + unsigned int lsr; + + while (tries--) { + lsr = readb (p->membase + (UART_LSR << p->regshift)); + if (lsr & UART_LSR_TEMT) + break; + udelay (10); + } +} + static void dw8250_serial_out(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; + /* Allow the TX to drain before we reconfigure */ + if (offset == UART_LCR) + dw8250_tx_wait_empty(p, 1000); + writeb(value, p->membase + (offset << p->regshift)); if (offset == UART_LCR && !d->uart_16550_compatible) |