Commit e5d6bd25 authored by Peter Collingbourne's avatar Peter Collingbourne Committed by Greg Kroah-Hartman
Browse files

serial: 8250_dw: Do not reclock if already at correct rate 



When userspace opens the console, we call set_termios() passing a
termios with the console's configured baud rate. Currently this causes
dw8250_set_termios() to disable and then re-enable the UART clock at
the same frequency as it was originally. This can cause corruption
of any concurrent console output. Fix it by skipping the reclocking
if we are already at the correct rate.

Signed-off-by: default avatarPeter Collingbourne <pcc@google.com>
Fixes: 4e26b134 ("serial: 8250_dw: clock rate handling for all ACPI platforms")
Cc: stable@vger.kernel.org
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240222192635.1050502-1-pcc@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 672448cc

drivers/tty/serial/8250/8250_dw.c

+3 −3
Original line number Diff line number Diff line
@@ -357,9 +357,9 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, 
	long rate;

	int ret;



	clk_disable_unprepare(d->clk);

	rate = clk_round_rate(d->clk, newrate);

	if (rate > 0) {

	if (rate > 0 && p->uartclk != rate) {

		clk_disable_unprepare(d->clk);

		/*

		 * Note that any clock-notifer worker will block in

		 * serial8250_update_uartclk() until we are done.
@@ -367,8 +367,8 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, 
		ret = clk_set_rate(d->clk, newrate);

		if (!ret)

			p->uartclk = rate;

	}

		clk_prepare_enable(d->clk);

	}



	dw8250_do_set_termios(p, termios, old);

}