sl-modem-daemon does not work on some hardware

Binary package hint: linux-source-2.6.22

The laptop I use for testing sl-modem-daemon (our winmodem support) has stopped working properly. In tribe 5, sl-modem-daemon worked fine. Now attempts to dial give NO CARRIER / ERROR immediately (without even waiting for dialtone).

The sl-modem-daemon binary package hasn't changed at all and it relies pretty directly on the relevant kernel interfaces (as accessed via alsa libraries). So I think this is a kernel regression.

The modem is supported in the kernel by snd-intel8x0m. Here is the output of lspci and a copy of /proc/asound cards (with the module loaded):

00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #1 (rev 03)
00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #2 (rev 03)
00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #3 (rev 03)
00:1d.3 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #4 (rev 03)
00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB2 EHCI Controller (rev 03)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev d3)
00:1e.2 Multimedia audio controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Audio Controller (rev 03)
00:1e.3 Modem: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Modem Controller (rev 03)
00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC Interface Bridge (rev 03)
00:1f.1 IDE interface: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) IDE Controller (rev 03)
00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) SMBus Controller (rev 03)
02:04.0 Network controller: Broadcom Corporation BCM4306 802.11b/g Wireless LAN Controller (rev 03)
02:06.0 CardBus bridge: Texas Instruments PCIxx21/x515 Cardbus Controller
02:06.2 FireWire (IEEE 1394): Texas Instruments OHCI Compliant IEEE 1394 Host Controller
02:0e.0 Ethernet controller: Broadcom Corporation BCM4401-B0 100Base-TX (rev 02)

 0 [ICH6 ]: ICH4 - Intel ICH6
                      Intel ICH6 with AD1981B at irq 22
 1 [Modem ]: ICH-MODEM - Intel ICH6 Modem
                      Intel ICH6 Modem at irq 17