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Commit 50aa193a authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: serial: f81534: fix division by zero on line-speed change 



commit 188c9c2e0c7f4ae864113f80c40bafb394062271 upstream.

The driver leaves the line speed unchanged in case a requested speed is
not supported. Make sure to handle the case where the current speed is
B0 (hangup) without dividing by zero when determining the clock source.

Fixes: 3aacac02 ("USB: serial: f81534: add high baud rate support")
Cc: stable@vger.kernel.org      # 4.16
Cc: Ji-Ze Hong (Peter Hong) <hpeter@gmail.com>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0d6bf63e

drivers/usb/serial/f81534.c

+7 −5
Original line number Diff line number Diff line
@@ -538,9 +538,6 @@ static int f81534_submit_writer(struct usb_serial_port *port, gfp_t mem_flags) 


static u32 f81534_calc_baud_divisor(u32 baudrate, u32 clockrate)

{

	if (!baudrate)

		return 0;



	/* Round to nearest divisor */

	return DIV_ROUND_CLOSEST(clockrate, baudrate);

}
@@ -570,9 +567,14 @@ static int f81534_set_port_config(struct usb_serial_port *port, 
	u32 baud_list[] = {baudrate, old_baudrate, F81534_DEFAULT_BAUD_RATE};



	for (i = 0; i < ARRAY_SIZE(baud_list); ++i) {

		idx = f81534_find_clk(baud_list[i]);

		if (idx >= 0) {

		baudrate = baud_list[i];

		if (baudrate == 0) {

			tty_encode_baud_rate(tty, 0, 0);

			return 0;

		}



		idx = f81534_find_clk(baudrate);

		if (idx >= 0) {

			tty_encode_baud_rate(tty, baudrate, baudrate);

			break;

		}