Linux Infrared HOWTO
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# 5.8. Linux/IrDA and APM

Fons Botman wrote: "When I hibernate my HP OmniBook 2000CT, (Fn-12 diskimage is written to disk, machine turns off completely) with irtty active and turn it on again, irda does not work. I can see it trying to reply to discovery frames it receives from a windows box, using irdadump on the OmniBook. but the windows PC does not see the replies. If I just kill irattach and remove irtty and serial, and start irattach again, it starts working again. Does this occur with other linux laptops also? Is it a problem in the serial device driver? " Also Pedro Figueiredo reported this problem for a Fujitsu LifeBook 735DX.

Answer by Dag Brattli: "Could you all check if the same thing is happening when your're using PPP (and not using IrDA). I guess the APM stuff shuts down the serial port, so that the driver will need to reinitialize it when waking up again. This is properly implemented by some of the PCMCIA drivers I know about, but I really don't think the serial driver gets any events from the APM system.

So here you have your own little kernel project. Start adding APM support to irport which will be the easiest thing (and also to the FIR drivers), then you can start adding a patch to the serial driver (if needed). Again I think the PCMCIA subsystem may be a good source on how to fix it properly."

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