usb devices are sensitive on vbus timings
i found
This ECN ensures that all USB peripherals have a detectable change in capacitance on VBus when they
are attached. This ensures that OTG devices and Embedded Hosts can detect attachment of peripherals
in the absence of VBus.
and
Specification Changes
The last sentence in Section 7.2.4.2 to be modified from:
“A minimum of 1.0uF is recommended for bypass across Vbus.”
To the following text:
“A USB device is required to expose a capacitance on the VBUS pin of its connector of CRPB. This
capacitance shall be greater than CRPB min for voltages on the VBUS pin from 0V to 5.25V,
regardless of whether the USB device is powered or unpowered.”


from early ( final, not pached with otg stuff , but valid ) usb standard
No device shall supply (source) current on VBUS at its upstream facing port at any time. From VBUS on its
upstream facing port, a device may only draw (sink) current. They may not provide power (my note: from 3,3v internal source ) to the pull-up resistor
on D+/D- unless VBUS is present

vbus is needed for that so let put 5v on vbus * to make peripherals happy

* joerg broke a annoying barrier between host and n900 when he finded how to enable boost mode on 24150