Re: serial flow control appears broken

Lee Howard
2007-07-27T20:06:40Z

Tilman Schmidt wrote:

>Lee Howard schrieb:
>
>
>>So, does this explain why I wouldn't have a problem at 115200 bps with
>>kernel 2.2.5 but why I do with 2.6.5 and 2.6.18? Both hardware and
>>software flow control work fine with 2.2.5 (meaning I don't see any
>>error message and I don't have any data corruption), but neither works
>>to avoid the "kernel: ttyS1: 1 input overrun(s)" and consequent data
>>corruption issue in 2.6.5 nor 2.6.18.
>>
>>Was there some associated application change in tty handling that needed
>>to occur between the 2.2 and 2.6 kernels to properly implement flow control?
>>
>>
>
>Could this be related?
>
>http://lkml.org/lkml/2007/7/18/245
>
>Quote:
>"I've recently found (using 2.6.21.4) that configuring a serial ports
>(ST16654) which use the 8250 driver using setserial results in the
>UART's FIFOs being disabled (unless you specify autoconfig)."
>
>

I'm not running setserial on the port, myself. But to test to see if it
is related, I included this code in the application:

#include <linux/serial.h>
....
struct serial_struct serial;
ioctl(modemFd, TIOCGSERIAL, &serial);
traceModemOp("modem xmit_fifo_size: %u", serial.xmit_fifo_size);

And I get this resulting logging:

"MODEM modem xmit_fifo_size: 16"

So it's clear from here that the xmit_fifo_size is set correctly on this
system.

Thanks,

Lee.