Serial Port Errors, Brio BA200 Under Linux

[David Darden]

The Brio BA200 generates receive frame errors on the serial port under Linux (Red Hat 6.1, 6.2, Suse 6.3, 6.4). The errors are very severe at high speed (115K to an external ISDN adapter), so that the port is unusable at high speed because of all the retransmitted packets (this eventually causes the connection to hang). Receive frame errors are 15 to 30 percent of all receive packets at high speed as reported by "ifconfig ppp0". Errors are less severe at lower speeds, but still show at speeds as low as 14.4 kbaud (as low as I tested). Errors show in either graphics or text mode (independent of X Windows). The errors show when using the most recent kernel update from Red Hat as of 7/4/00. The serial port appears to work fine at high speed under Windows. The ISDN equipment works fine on another PC (an old Gateway Pentium 60) under Red Hat 6.1. Putting the serial port in polling mode hangs the system. Using a serial port on a SIIG dual port PCI expansion card shows the same symptoms. The symptoms exist on two separate Brio's (so it looks like the issue is not board failure). The symptoms exist with all third party equipment removed, and with or without allowing the system BIOS to select IRQ and I/O address for the port. Various options with the setserial command have no effect. Neither does irqtune. It seems like there is a race condition on the PCI bus under Linux with the serial port of the Brio BA200.

Has anyone observed this problem and is there a solution (other than running at low speed, using Windows, using eth0 routed from another PC instead of ppp0, or replacing the motherboard)? Does anyone know if replacing the motherboard in the Brio BA200 with the Intel CA810E will work (and will work with the CPU and RAM from the Brio)? Thanks.