[PATCH] serial: 8250_dw: Honor clk_round_rate errors in dw8250_set_termios

[PATCH] serial: 8250_dw: Honor clk_round_rate errors in dw8250_set_termios

[Heiko Stuebner]

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.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
 drivers/tty/serial/8250/8250_dw.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 6ee55a2d47bb..223ac234ddb2 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -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)
-- 
2.11.0

Re: [PATCH] serial: 8250_dw: Honor clk_round_rate errors in dw8250_set_termios

[Andy Shevchenko]

On Tue, Feb 28, 2017 at 5:17 AM, Heiko Stuebner <heiko@sntech.de> wrote:
> 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.
>

FWIW:
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
> ---
>  drivers/tty/serial/8250/8250_dw.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index 6ee55a2d47bb..223ac234ddb2 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -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)
> --
> 2.11.0
>



-- 
With Best Regards,
Andy Shevchenko