On Mon, 2016-04-25 at 15:03 +0200, David Müller wrote:
> Since commit 21947ba6 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 correctly.
>
> The attached patch fixes this by restoring the old behavior for the
> B0
> case.
>
I'm not sure this is a right implementation of the fix.
Intention, which is not described in the commit message, as I can see is
to map B0 to B9600(?).
Straight forward one liner can do that I think:
/* Take care about B0, i.e. map it to B9600 */
fuart = fuart ? fuart : 9600 * 16;
Alternatively we might leave the speed as is:
fuart = fuart ? fuart : p->uartclk;
>
> Signed-off-by: David Müller <d.mueller@xxxxxxxxx>
> ---
> drivers/tty/serial/8250/8250_pci.c | 26 ++++++++++++++++----------
> 1 file changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_pci.c
> b/drivers/tty/serial/8250/8250_pci.c
> index 98862aa..610c747 100644
> --- a/drivers/tty/serial/8250/8250_pci.c
> +++ b/drivers/tty/serial/8250/8250_pci.c
> @@ -1377,17 +1377,23 @@ byt_set_termios(struct uart_port *p, struct
> ktermios *termios,
> unsigned long m, n;
> u32 reg;
>
> - /* Get Fuart closer to Fref */
> - fuart *= rounddown_pow_of_two(fref / fuart);
> + if (fuart) {
> + /* Get Fuart closer to Fref */
> + fuart *= rounddown_pow_of_two(fref / fuart);
>
> - /*
> - * For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M
> the
> - * dividers must be adjusted.
> - *
> - * uartclk = (m / n) * 100 MHz, where m <= n
> - */
> - rational_best_approximation(fuart, fref, w, w, &m, &n);
> - p->uartclk = fuart;
> + /*
> + * For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M
> and 4M the
> + * dividers must be adjusted.
> + *
> + * uartclk = (m / n) * 100 MHz, where m <= n
> + */
> + rational_best_approximation(fuart, fref, w, w, &m,
> &n);
> + p->uartclk = fuart;
> + } else {
> + m = 2304;
> + n = 3125;
> + p->uartclk = 73728000;
> + }
>
> /* Reset the clock */
> reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n <<
> BYT_PRV_CLK_N_VAL_SHIFT);
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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