Thanks for all of your replies.

I was already familiar with that method of shorting the D+/D- lines.

As i was saying the issue is fast charging while phone is being used as as a power hungry 3.5 G modem that is connected to the wireless router in a dedicated mode through a self-powered and expensive USB hub. The data lines are needed for data, and although Y cable injects the additional 500mA from a second port - I cant short the data lines because I need the internet to work at the same time.

I have read the datasheets for the charger that N900 uses (charger chip bq24150 ) and they explain that i2cset can be used to set the charge level by manipulating Iil_limits registers.
My conclusion is that this is software settable parameter - but no one had seemed to have talked about it thus far. I guess most people are fine with not using the phone while it is charging, or maybe content with the battery swap.

So mine is a diferrent need/use case.

I was just not so sure to try it on my own, without first asking more knowledgable people that might have already done it themselves.

I guess that if no one can contribute the actual i2cset command - I will have to try to figure it out myself. I will first attempt to use i2c to read the register's data for 100mA and then 500mA - and once I am certain that I have the right chip address, mask, etc. I will try setting it myself and read /sys values to confirm that it works.

If I get lucky - I will share with the forum how it is done.

Thanks anyhow.

netC