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    Subject[PATCH 4.4 039/118] serial: 8250_mid: fix divide error bug if baud rate is 0
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

    commit 47b34d2ef266e2c283b514d65c8963c2ccd42474 upstream.

    Since the commit c1a67b48f6a5 ("serial: 8250_pci: replace switch-case by
    formula for Intel MID"), the 8250 driver crashes in the byt_set_termios()
    function with a divide error. This is caused by the fact that a baud rate of 0
    (B0) is not handled properly. Fix it by falling back to B9600 in this case.

    Reported-by: "Mendez Salinas, Fernando" <fernando.mendez.salinas@intel.com>
    Fixes: c1a67b48f6a5 ("serial: 8250_pci: replace switch-case by formula for Intel MID")
    Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/tty/serial/8250/8250_mid.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/drivers/tty/serial/8250/8250_mid.c
    +++ b/drivers/tty/serial/8250/8250_mid.c
    @@ -149,6 +149,9 @@ static void mid8250_set_termios(struct u
    unsigned long w = BIT(24) - 1;
    unsigned long mul, div;

    + /* Gracefully handle the B0 case: fall back to B9600 */
    + fuart = fuart ? fuart : 9600 * 16;
    +
    if (mid->board->freq < fuart) {
    /* Find prescaler value that satisfies Fuart < Fref */
    if (mid->board->freq > baud)

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