RND_TYPE_RNG question concerning rate of random bits production

[Frank Zerangue <frank.zerangue%gmail.com@localhost>]

I am writing a driver for an arm random number generator accelerator to provide 
a source of random bits to rnd_pool.

How does one know at what rate to supply random bits to the pool using 
rnd_add_data()? Assume for a moment that more bits/sec can be generated than 
are needed, what criteria should be used to decide the rate to provide bits to 
the pool? Is there any feedback mechanism that can be used to govern the flow?

There are 3 instances of an RNGA driver in the source tree that I found, two of 
which provide 32 bits every 10msecs or so, and a third that provide an unknown 
number of bits (assuming > 32bits) every 100msecs. Does anyone know the 
reasoning used for the examples described. (i386/pci/glxsb.c, x86/pci/fwrng.c, 
x86/x86/via_padlock.c)

Thanks
--
Frank Zerangue
frank.zerangue%gmail.com@localhost