Help: Bios not setting IRQ for a PCI modem

Help: Bios not setting IRQ for a PCI modem

Post by R Kanna » Thu, 03 Jan 2002 01:25:37


I have installed a US Robotics PCI modem (Plug n Play)
and it works fin in Windoze. But in linux (RH 7.0), since
the BIOS does not set the IRQ, the modem does not
seem to be responding..

"lspci -vv" returns for the modem:

00:09.0 Serial controller: US Robotics/3Com 56K FaxModem Model 5610 (rev 01) (prog-if 02 [16550])
 Subsystem: US Robotics/3Com: Unknown device 00d3
 Control: I/O+ Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
 Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
 Interrupt: pin A routed to IRQ 0
 Region 0: I/O ports at d000
 Capabilities: [dc] Power Management version 2
  Flags: PMEClk- DSI- D1- D2+ AuxCurrent=0mA PME(D0+,D1-,D2+,D3hot+,D3cold+)
  Status: D0 PME-Enable- DSel=0 DScale=2 PME-

and the 'driver' for the modem from USR (3ComMdm) set serial ports as follows.
'setserial' returns..

/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
/dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 3
/dev/ttyS3, UART: 16550A, Port: 0xd000, IRQ: 0

which obviously does not work for the modem (/dev/ttyS3). The modem takes
in 'AT' commands like 'ATZ' and I can use 'ATDT' for dialing out bur it is not
responding with 'OK'.

I even tried changing the BIOS set up to indicate a non PnP OS, which case I get
the IRQ set at 9 (which apparently is the same as 2) and 'setserial /dev/ttyS3' returns

/dev/ttyS3, UART: 16550A, Port: 0xd000, IRQ: 2

and the modem does not even take in any commands.

Thanks for any help.