I tried the repository linked in my previous message and I can confirm that the dsl part is half working. The VRX518 gets the signal, but no data is received. I digged into the vrx518_tc_drv but not enough to find the culprit. I think that the problem is caused by some interrupts not firing when the dsl chip receives packets. Probably somewhere in the the sw_plat.c file connected to the rx section... @sch-m Do you have any idea about it?
P.s. Just for clarification, i think that ltq-vdsl-app creates the "pipes" in /tmp/pipe so that is possible to get information from the dsl chip. Although my version was not working correclty, it wasn't too old to support the vrx518. I tried an even newer version and it does't work either. However Martin's repository is cleaner and better organized than mine so I advice to start again from his repo.