each DVB driver has its own time-out value for tuning (maximum time required to get a lock).
Some tuners have rather short time-out, others - relatively long.
This time-out value is returned by the driver (through fe_get_tune_settings() call).
And this value is hard-coded into the driver.

The problem with vTuner is: it uses it's own time out value (and it does not matter what a real time-out value is used in 3rd party tuner, connected to this vTuner interface).
As a result, vtuner aborts tuning before 3rd party tuner gets a lock (if that 3rd party tuner uses longer time-out then vtuner).
Particularly, genpix DVB driver uses 800ms as a min_delay_ms (while vTuner uses something shorter, like 400-500ms).
And very often vtuner reports "no lock" just because it does not wait long enough.

It would be a big help if vtuner would pass this time-out value (tune->min_delay_m) from "slave" driver (via additional command "MSG_GET_TUNE_SETTINGS").