Aparently Nicolas Maître wrote (for some reason I only got the followup by Takashi Iwai):
In my case, model=hp-dv7-4000 doesn't fully solve the problem. The subwoofer works but it is not mapped as such. After some tests, it seems that the alsa's speakers rear left and rear right are mapped to the subwoofer. The front ones are alright. With the model=hp-dv5 that I'm using, the subwoofer isnt recognized at all, but the rear speakers are correctly mapped.
I've also tested model=hp-dv5 and I think - I'm not sure - it doesn't use the subwoofer same as with Nicolas.
What's sure however is that it's showing the same symptoms as model=hp-dv7-4000 after wakeup as described here:
http://article.gmane.org/gmane.linux.alsa.devel/103836
Nicolas, are you able to suspend your machine while playing (or not) sound? Does your sound-system come up in order again after wakeup? *t