Neo Sound and USB Questions

[Ian Stirling]

Brad Midgley wrote:
> Hi
> 
> 
>>But most of them just power the 5V line. This is bad with 99% of the bad
>>behaving usb gadgets out there.
>>But Neo is prolite and asks the host if it could draw it's 500mA and if
>>not only takes 100mA out of the bus.
> 
> 
> this excessive politeness rules out hand-crank charger, solar cell,
> battery-to-usb, and every auto-usb adapter out there. It's overkill.
> 
> the usb spec requires the hub to reply to the request for more power.
> no reply within xx ms means there is no hub to ask. At this point it
> should be pragmatic and just use the @#&* 500mA.
> 
> I tried to hunt this down in the source and I think it's in two
> places--uboot when off and the kernel when on. It was very hard to
> figure out who drives the control.

Three places.
There is hardware policy, which is set by uboot/the kernel, in the power 
control chip.
Well - four places - some of it is configured by resistors on the board.