From 2c9e56b580d556c415d805bc314af1d08c6708d8 Mon Sep 17 00:00:00 2001 From: Heiko Stuebner Date: Tue, 28 Feb 2017 04:09:22 +0100 Subject: [PATCH v2] serial: 8250_dw: Honor clk_round_rate errors in dw8250_set_termios 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 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") enabled set_termios callback in all cases, not only ACPI. Fixes: 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") Signed-off-by: Heiko Stuebner Reviewed-by: Andy Shevchenko --- There is also another patch floating around, fixing a separate issue on top of this one: "serial: 8250_dw: Fix breakage when HAVE_CLK=n" changes in v2: - adapt commit message to make it more explicit, that this is a somewhat critical fix - add Andy's Reviewed-by 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