Re: serial flow control appears broken

[Lee Howard <faxguy@howardsilvan.com>]

Paul Fulghum wrote:

> Tilman Schmidt wrote:
>
> > 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)."
>
>
> That would make sense.
>
> Lee's error is a hardware FIFO overrun which could occur
> if the FIFO is being disabled as described in your
> link (by trying to set the uart type with setserial).


I'm not using setserial on this port, myself.  If something in init is 
calling on setserial then I don't know about it.

That said, tests on the serial port from within the application show 
that xmit_fifo_size is set to 16 as it should be.

I wrote up a little test app:

   struct serial_struct serial;
   ioctl(modemFd, TIOCGSERIAL, &serial);
   printf("            type: %d\n", serial.type);
   printf("            line: %d\n", serial.line);
   printf("            line: %u\n", serial.port);
   printf("             irq: %d\n", serial.irq);
   printf("           flags: %d\n", serial.flags);
   printf("  xmit_fifo_size: %d\n", serial.xmit_fifo_size);
   printf("  custom_divisor: %d\n", serial.custom_divisor);
   printf("       baud_base: %d\n", serial.baud_base);
   printf("     close_delay: %u\n", serial.close_delay);
   printf("         io_type: 0x%X\n", serial.io_type);
   printf("reserved_char[0]: 0x%X\n", serial.reserved_char[0]);
   printf("            hub6: %d\n", serial.hub6);
   printf("    closing_wait: %u\n", serial.closing_wait);
   printf("   closing_wait2: %u\n", serial.closing_wait2);
   printf(" iomem_reg_shift: %u\n", serial.iomem_reg_shift);
   printf("       port_high: %u\n", serial.port_high);
   printf("     reserved[0]: %d\n", serial.reserved[0]);

Here's the output:

           type: 4
           line: 1
           line: 760
            irq: 3
          flags: 1358954688
 xmit_fifo_size: 16
 custom_divisor: 0
      baud_base: 115200
    close_delay: 500
        io_type: 0x0
reserved_char[0]: 0x0
           hub6: 0
   closing_wait: 30000
  closing_wait2: 0
iomem_reg_shift: 0
      port_high: 0
    reserved[0]: 0

Thanks,

Lee.
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