DRV8308: DRV8308 Parameters tuning

Part Number:DRV8308

Hi Teams

I am helping the customer to tune DRV8308's parameter and encounter several problems need your help:

Vin=24V Using 3 single end hall input  Operating in Clock frequency Mode.

1. I found the FGOUT(Set to output the U hall signal) signal frequency can't match CLKIN signal's frequency (Can't lock the speed) when the CLKIN lower than 30Hz
2. Can I enable the bypass filter and disable the bypass compensator at the same time.?( The motor fails to start up when the bypass compensator is enabled in many situations.)
3. What MOD120 used for? Are this parameter only been used in 180 commutations?
4. Are the hall sensor compensation (relative with "Advance" register) only active in 180 commutations?
5. Are close loop speed control can only be used in 180 commutations? Can we achieve as low as 400 RPM with DRV8308?

Thanks in advance