Knowledgebase

Issue:

The Linux 2.6.9 (or higher) kernel detects the Perle UltraPort SI or Speed LE card as a standard serial device and causes the perle-serial driver to fail detection of the card.

dmesg (boot messages) will display:

Serial: 8250/16550 driver $Revision: 1.90 $ 8 ports, IRQ sharing enabled
ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
ttyS4 at MMIO 0xe0800000 (irq = 9) is a 16550A
ttyS5 at MMIO 0xe0800200 (irq = 9) is a 16550A

Cause:
The vendor ID used by the Perle UltraPort SI or Speed LE cards has been added to the 8250 driver code. If the 8250 serial device driver is loaded first, it will take control of any installed UltraPort SI or Speed LE cards and the perle-serial driver will not be able to detect the card.

Solution:

Rebuild the kernel with modular support for the 8250/16550 serial driver.

Device Drivers -> Character devices -> Serial drivers -->

8250/16550 and compatible serial support

Then you can load the perle-serial module before the 8250 module.