diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_dw.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_dw.c | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 7e638997bfc2..10b0aca8ae19 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -256,25 +256,31 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, struct ktermios *old) { unsigned int baud = tty_termios_baud_rate(termios); + unsigned int target_rate, min_rate, max_rate; struct dw8250_data *d = p->private_data; long rate; - int ret; + int i, ret; if (IS_ERR(d->clk) || !old) goto out; - clk_disable_unprepare(d->clk); - rate = clk_round_rate(d->clk, baud * 16); - if (rate < 0) - ret = rate; - else if (rate == 0) - ret = -ENOENT; - else - ret = clk_set_rate(d->clk, rate); - clk_prepare_enable(d->clk); + /* Find a clk rate within +/-1.6% of an integer multiple of baudx16 */ + target_rate = baud * 16; + min_rate = target_rate - (target_rate >> 6); + max_rate = target_rate + (target_rate >> 6); - if (!ret) - p->uartclk = rate; + for (i = 1; i <= UART_DIV_MAX; i++) { + rate = clk_round_rate(d->clk, i * target_rate); + if (rate >= i * min_rate && rate <= i * max_rate) + break; + } + if (i <= UART_DIV_MAX) { + clk_disable_unprepare(d->clk); + ret = clk_set_rate(d->clk, rate); + clk_prepare_enable(d->clk); + if (!ret) + p->uartclk = rate; + } out: p->status &= ~UPSTAT_AUTOCTS; |