[plug] Can I force 500ma max power for usb?

Pavel Volský pavel.volsky at gmail.com
Wed Nov 6 07:00:50 UTC 2013

Hello William,
my first thought was - how can you be sure it is not the phone's logic
restricting the power allowed to the phone?
On the other hand my second thought was - to shut up because i know very
little about this. But I really would like to know more how you can measure
and set this in Linux.

So, if you have any know-how resources, send me a link please.

Ps - what kind of phone do you have? I can try some tests on my SGS 3.

On 6 Nov 2013 11:42, "William Kenworthy" <billk at iinet.net.au> wrote:

> I would like to override a USB hubs max power setting:
> I have a samsung phone that depending on the cable gets enumerated and
> sets max power from the usb hub (PC, Laptop etc.) to 96ma.
> For some reason if it doesn't get enumerated it gets a significantly
> faster charge rate (I suspect that it piggybacks an existing connection
> that has already been negotiated to 500ma.)  For practical purposes it
> works well for this small subset of cables ... which is my current dilemma.
> If I only have standard full function usb cables (4 wire, independent
> earths) that enumerate fine, except they negotiate 96ma (less than the
> 100ma default if accurate!), can I override the negotiation and set max
> power to 500ma? - note I am not trying to force 500ma current draw but
> set the threshold to 500ma.
> OS is gentoo but hardware is either ASUS, Dell or Apple ... same
> problem, same 96ma which supports the fact that more than this current
> is really available if I can access it.
> BillK
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