[clug] A "mount" defeat - was Re: Persuading Debian to talk to an Android tablet via USB?

Daniel Pittman daniel at rimspace.net
Thu Oct 21 06:20:48 MDT 2010

Hal Ashburner <hal at ashburner.info> writes:
>  On 21/Oct/10 10:37 PM, Alex Satrapa wrote:
>> The theory is that a USB port controller is supposed to be able to negotiate
>> with devices about whether to provide power, and if so, how much. The USB
>> port is supposed to be able to supply up to 1.5A, and some high-power
>> devices will request the "whole nine yards"
> Or more, eg the dual usb cable plugs that power 2.5" usb hard drives, 3G
> modems and such. My understanding is modern usb ports actually supply more
> than spec when requested meaning you only have to plug into one port. My
> current laptop has no issue with one port, my older IBM T42 required two ports
> for the same drive.
> Anyway an SD reader shouldn't require loads of power, just about any usb port
> /should/ do. But I haven't got a better guess as to why felix's isn't working
> beyond maybe it's just a flaky PoS. Who knows?

At this point I would be guessing that the USB service on his motherboard is
dubious, especially since using a different port produced better results with
the same client device.

Which might also explain why the Android device didn't work as expected,
because a host-side fault would cause all sorts of clients to fail.

✣ Daniel Pittman            ✉ daniel at rimspace.net            ☎ +61 401 155 707
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