2.5.42: IrDA issues

[ALESSANDRO.SUARDI]

I have a PPP over IrDA connection to my Nokia phone; under 2.4.20-preX I have no
 problem keeping the link up, while in 2.5.4x it fails in a very short time like this:

Oct 13 01:13:13 dolphin kernel: IrLAP, no activity on link!
Oct 13 01:13:11 dolphin kernel: NETDEV WATCHDOG: irda0: transmit timed out
Oct 13 01:13:11 dolphin kernel: irda0: transmit timed out
Oct 13 01:13:13 dolphin kernel: IrLAP, no activity on link!
Oct 13 01:13:13 dolphin kernel: NETDEV WATCHDOG: irda0: transmit timed out
Oct 13 01:13:13 dolphin kernel: irda0: transmit timed out
Oct 13 01:13:13 dolphin pppd[5378]: Modem hangup
Oct 13 01:13:13 dolphin pppd[5378]: Connection terminated.
Oct 13 01:13:13 dolphin pppd[5378]: Connect time 1.8 minutes.
Oct 13 01:13:13 dolphin pppd[5378]: Sent 19541 bytes, received 35933 bytes.
Oct 13 01:13:13 dolphin pppd[5378]: Exit.

I also get the transmit timed out spam (why one with WATCHDOG and one without ?)
 in 2.4.20-pre but the IrLAP line isn't there. And the GPRS link stays up...

Thanks in advance for any insight,

--alessandro