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serial: 8250_dw: Honor clk_round_rate errors in dw8250_set_termios

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clk_round_rate returns a signed long and may possibly return errors
in it, for example if there is no possible rate.

Till now dw8250_set_termios ignored any error, the signednes and would
just use the value as input to clk_set_rate. This of course falls apart
if there is an actual error, so check for errors and only try to set
a rate if the value is actually valid.

This turned up on some Rockchip platforms after commit
6a171b2993 ("serial: 8250_dw: Allow hardware flow control to be used")
enabled set_termios callback in all cases, not only ACPI.

Fixes: 6a171b2993 ("serial: 8250_dw: Allow hardware flow control to be used")
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Heiko Stuebner 2017-03-09 07:41:16 +01:00 committed by Greg Kroah-Hartman
parent 4495c08e84
commit 09498087f9
1 changed files with 5 additions and 2 deletions
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7
drivers/tty/serial/8250/8250_dw.c
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@ -257,7 +257,7 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
{
unsigned int baud = tty_termios_baud_rate(termios);
struct dw8250_data *d = p->private_data;
unsigned int rate;
long rate;
int ret;
if (IS_ERR(d->clk) || !old)
@ -265,7 +265,10 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
clk_disable_unprepare(d->clk);
rate = clk_round_rate(d->clk, baud * 16);
ret = clk_set_rate(d->clk, rate);
if (rate < 0)
ret = rate;
else
ret = clk_set_rate(d->clk, rate);
clk_prepare_enable(d->clk);
if (!ret)