altpll "loop filter resistance" parameter: resistance to filtercap or to charge pump?

Hi, the altpll reconfiguration interface has a parameter called "loop filter resistance".

Is this the resistance imposed between the charge pump and the VCO control node, or is it the resistance between the VCO control node and the filter capacitor (i.e. the capacitor whose capacitance is one of the other parameters)?

Put another way: is this R1 or R2 in the figure below ("from PLL" means "from charge pump")?

If it matters, this is for a Cyclone III.

Thanks.