From: Dave Airlie When using register_serial the xmit_fifo_size parameter is accepted by the 8250 driver, and copied to the uart_port fifosize parameter, however autoconfigure then comes along and overrides this from the dfl_xmit_fifo_size, This patch checks if fifosize is 0 and if it is updates from the default, otherwise it accepts the value, --- 25-akpm/drivers/serial/8250.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletion(-) diff -puN drivers/serial/8250.c~serial-fifo-size-is-ignored drivers/serial/8250.c --- 25/drivers/serial/8250.c~serial-fifo-size-is-ignored 2004-05-11 01:37:32.055884376 -0700 +++ 25-akpm/drivers/serial/8250.c 2004-05-11 01:37:32.060883616 -0700 @@ -697,7 +697,8 @@ static void autoconfig(struct uart_8250_ #endif serial_outp(up, UART_LCR, save_lcr); - up->port.fifosize = uart_config[up->port.type].dfl_xmit_fifo_size; + if (up->port.fifosize==0) + up->port.fifosize = uart_config[up->port.type].dfl_xmit_fifo_size; up->capabilities = uart_config[up->port.type].flags; if (up->port.type == PORT_UNKNOWN) _