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UPSTREAM: USB: serial: f81534: fix division by zero on line-speed change

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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: 3aacac02f3 ("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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I87d08ff845ec24adae387ce829e56ff34f85ddb6
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit c8bf31a00f)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Johan Hovold
2022-11-29 15:18:19 +01:00
committed by Greg Kroah-Hartman
parent d81b6e6e88
commit 4fa772e757
1 changed files with 7 additions and 5 deletions
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12
drivers/usb/serial/f81534.c
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@@ -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) static u32 f81534_calc_baud_divisor(u32 baudrate, u32 clockrate)
{ {
if (!baudrate)
return 0;
/* Round to nearest divisor */ /* Round to nearest divisor */
return DIV_ROUND_CLOSEST(clockrate, baudrate); 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}; u32 baud_list[] = {baudrate, old_baudrate, F81534_DEFAULT_BAUD_RATE};
for (i = 0; i < ARRAY_SIZE(baud_list); ++i) { for (i = 0; i < ARRAY_SIZE(baud_list); ++i) {
idx = f81534_find_clk(baud_list[i]); baudrate = baud_list[i];
if (baudrate == 0) {
tty_encode_baud_rate(tty, 0, 0);
return 0;
}
idx = f81534_find_clk(baudrate);
if (idx >= 0) { if (idx >= 0) {
baudrate = baud_list[i];
tty_encode_baud_rate(tty, baudrate, baudrate); tty_encode_baud_rate(tty, baudrate, baudrate);
break; break;
} }