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Date: Tue, 15 Feb 2005 17:55:21 -0600
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From: "Eric N. Johnson (ACD)" <ejohnson@acdstar.com>
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Subject: Re: How to set a custom baud rate using 2.6 linux distro on
 MPC5200 based board?
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>I'm trying to set a custom baud rate (500KBaud, in case anyone cares) on 
>one of the PSCs on a MPC5200 board.
[snip]
>   serial_info.flags = ASYNC_SPD_CUST | ASYNC_LOW_LATENCY;
>    serial_info.custom_divisor = 48;  // clock on FTDI chip / 48 == 500KB
>
>    if ( ioctl(tty_fd, TIOCSSERIAL, &serial_info ) < 0) {
>      perror("config_serial_port: ioctl TIOCSSERIAL");
>      return(-1);
>    }
>
>This compiled fine under the ppc cross-dev tools we have but it fails with 
>an "invalid argument" error when run on the ppc board.

It looks like this code was written for an FTDI serial port.  The FTDI is a 
USB to Serial converter that handles baud rate generation very differently 
from a standard UART.

Eric