diff options
Diffstat (limited to 'drivers/tty/serial')
| -rw-r--r-- | drivers/tty/serial/8250/8250_pci.c | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index e6656036c503..f7d89440076a 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -1349,29 +1349,33 @@ pericom_do_set_divisor(struct uart_port *port, unsigned int baud, { int scr; int lcr; - int actual_baud; - int tolerance; - for (scr = 5 ; scr <= 15 ; scr++) { - actual_baud = 921600 * 16 / scr; - tolerance = actual_baud / 50; + for (scr = 16; scr > 4; scr--) { + unsigned int maxrate = port->uartclk / scr; + unsigned int divisor = max(maxrate / baud, 1U); + int delta = maxrate / divisor - baud; - if ((baud < actual_baud + tolerance) && - (baud > actual_baud - tolerance)) { + if (baud > maxrate + baud / 50) + continue; + if (delta > baud / 50) + divisor++; + + if (divisor > 0xffff) + continue; + + /* Update delta due to possible divisor change */ + delta = maxrate / divisor - baud; + if (abs(delta) < baud / 50) { lcr = serial_port_in(port, UART_LCR); serial_port_out(port, UART_LCR, lcr | 0x80); - - serial_port_out(port, UART_DLL, 1); - serial_port_out(port, UART_DLM, 0); + serial_port_out(port, UART_DLL, divisor & 0xff); + serial_port_out(port, UART_DLM, divisor >> 8 & 0xff); serial_port_out(port, 2, 16 - scr); serial_port_out(port, UART_LCR, lcr); return; - } else if (baud > actual_baud) { - break; } } - serial8250_do_set_divisor(port, baud, quot, quot_frac); } static int pci_pericom_setup(struct serial_private *priv, const struct pciserial_board *board, |