serial: 8250_pci: change BayTrail default uartclk

The Intel BayTrail HSUART power-on default reference clock is 44.2368 MHz,
but 73.728 MHz provides 0% error for additional "conventional" baud rates
above 460800 (e.g. 576000, 921600, and 1152000).

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index a3dbc4d..b14bcba 100644 (file)
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1401,9 +1401,9 @@ byt_set_termios(struct uart_port *p, struct ktermios *termios,
                p->uartclk = 40000000;
                break;
        default:
-               m = 6912;
-               n = 15625;
-               p->uartclk = 44236800;
+               m = 2304;
+               n = 3125;
+               p->uartclk = 73728000;
        }
 
        /* Reset the clock */
@@ -3470,6 +3470,10 @@ static struct pciserial_board pci_boards[] = {
                .base_baud      = 921600,
                .reg_shift      = 2,
        },
+       /*
+        * Intel BayTrail HSUART reference clock is 44.2368 MHz at power-on,
+        * but is overridden by byt_set_termios.
+        */
        [pbn_byt] = {
                .flags          = FL_BASE0,
                .num_ports      = 1,