How to make use of IrDA

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The purpose of this document is to get the IrDA hardware in your ThinkPad operational, setting up communication to other devices is not covered. However, the external links section can prove useful for this.

Serial IR (SIR)

SIR is limited to serial datarates up to 115.2Kb/s

Kernel configuration

Linux 2.4 kernel config

Edit /etc/modules.conf and add the following lines 

alias tty-ldisc-11 irtty
alias char-major-161 ircomm-tty

Linux 2.6 kernel config

Edit /etc/modprobe.conf and add the following lines 

alias tty-ldisc-11 irtty-sir
alias char-major-161 ircomm-tty

Fast IR (FIR)

FIR is the preferred mode of IrDA operation and operates at a bandwidth of 4 Mbps

The chips FIR mode first needs to be activated using the ISA PnP or BIOS method.

Hint:
Regardless of which method you use, you will still have to set the dongle_id and run setserial as shown further below

ISA PnP support for nsc-ircc

Starting with the 2.6.17-rc1 kernel, the nsc-ircc driver has ISA PnP support, and seperate patching is no longer required.

If you have an older 2.6 kernel, here are some patches, that allow the loading of the driver without the below BIOS change.

ISA PnP support seems necessary in some cases (e.g., ThinkPad T43 and kernel 2.6.14 and 2.6.15).

Changing BIOS settings

For older kernels (prior to 2.6.17-rc1), the easiest way to activate FIR mode is by entering BIOS setup during boot-up by pressing F1 when prompted. Then, selecting 'Config' followed by 'Infrared' will allow you to control the IrDA operation. Here you will need to select the option to Enable the infra-red port, and ensure the proper resources are set (typically: IO 0x2f8 and IRQ 3). Be sure to save the changes, and then Exit.

NOTE!
Changing these BIOS settings does not affect Windows 2000 or XP operating systems, but may cause resource issues in older windows versions, or other legacy operating systems.
ATTENTION!
If you change the BIOS settings for IO, IRQ or DMA of the IrDA port, remember to do so accordingly on all examples in this page when applying them to your ThinkPad.

Kernel configuration

Linux 2.4 kernel config

Edit /etc/modules.conf and add the following lines 

alias irda0 nsc-ircc
options nsc-ircc dongle_id=0x09 io=0x2f8 irq=3 dma=3
pre-install nsc-ircc setserial /dev/ttyS1 uart none port 0 irq 0

Linux 2.6 kernel config

Edit /etc/modprobe.conf and add the following lines 

alias irda0 nsc-ircc
options nsc-ircc dongle_id=0x09 io=0x2f8 irq=3 dma=3
install nsc-ircc /bin/setserial /dev/ttyS1 uart none port 0 irq 0; /sbin/modprobe --ignore-install nsc-ircc

The install line is a work-around for the 8250 serial driver taking over the device, and may not be needed in certain distributions.

Gentoo kernel config

Edit / Create /etc/modules.d/nsc-irrc and add the following lines 

alias irda0 nsc-ircc
options nsc-ircc dongle_id=0x09 io=0x2f8 irq=3 dma=3

Edit /etc/modules.autoload.d/kernel-2.6 and add the following lines 

nsc-ircc

If you have serial support build in the kernel, switch it to a module and add it after nsc-ircc to advoid io base and irq conflict. For kernel 2.4, same as 2.6 changing the path to modules.autoload.d/kernel-2.4.

Debian Sarge/Etch kernel config

Install irda-utils and set it up for serial port emulation. Edit /etc/modprobe.d/irda-utils and add/change the following lines: 

alias irda0 nsc-ircc
options nsc-ircc dongle_id=0x09 io=0x2f8 irq=3 dma=3

Edit / create /etc/modules.conf and add the following line before any references to 8250*, if any: 

nsc-ircc

Make sure that module-init-tools has a chance to iterate over /etc/modules.conf before udev does the initial pci hotplug (this is a problem at least in Debian Sarge, when using backported udev packages): 

# cp /etc/rcS.d/S20module-init-tools /etc/rcS.d/S03module-init-tools

Note that at S03, module-init-tools cannot run depmod for you, so either do it manually before you reboot into a new kernel, or reboot twice to get it to work right. This is also the reason for using cp instead of mv.

If you have the regular serial port drivers as modules, that's it. Otherwise, try adding the install line described in the Linux 2.6 kernel config section, above, or compile them as modules instead of built-in.

Known problems

  • If the FIR mode is not activated, attempts to load the nsc-ircc module will result in an error in syslog of "Wrong chip version ff".
  • After suspend the nsc-ircc module needs to be manually reloaded
  • If module reloading does not work after a suspend, try reactivating the IrDA port as well:
rmmod nsc_ircc
echo disable > /sys/devices/pnp0/00\:0d/resources
echo activate > /sys/devices/pnp0/00\:0d/resources
modprobe nsc_ircc
The value pnp0/00\:0d can vary - look for a resources file containing the appropriate irq/dma/io values, e.g., using # grep 0x2f8 /sys/devices/pnp*/*/resources .
NOTE!
The power management issues should be resolved starting with the 2.6.17-rc1 kernel.

Some other things you might want to do with IrDA

  • add fast PPP support:
# modprobe irnet
  • if needed, limit further the size of the transmit window
# echo 1 > /proc/sys/net/irda/max_tx_window
  • set the connection speed to 4Mbit in FIR mode:
# echo 4000000 > /proc/sys/net/irda/max_baud_rate

LIRC and IrDA

Usually, IrDA port's are not compatible with LIRC, but you may have luck using lirc_sir.

If loading the lirc_sir module shows something like the following in # dmesg output, you are lucky and can use LIRC with the IrDA port to remote control your ThinkPad. 

lirc_sir: I/O port 0x02f8, IRQ 3.
lirc_sir: Installed.

External Sources

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