Re: USB product ID varies between kernels/distributions?

David Schwartz wrote:
On Dec 19, 2:56 pm, Janaka <jana...@xxxxxxxxxxxx> wrote:


I think David is spot on. USB devices may have internal configurable
units called Functions. Most low cost devices just implement 1
Function so you dont see any difference. Good quality USB devices may
contain multiple functions and enable/disable them depending of
conditions like available Power, USB Hub speed or anything else that
the USB standard has information for. This enabling/disabling is
totally under the control of the device firmware.
The firmware could also conditionally change the Vendor or Product IDs
as well. It is also under full firmware control.
The question is what is the difference in the HUB/Hardware of the
computers that make the product do this ?

They're all three different hardware: an Asus Mobo with an Athlon XP, the grabber is plugged into a hub which is then plugged into the motherboard (tried the hub on the notebook, but that didn't work, also tried a D-Link DUB-H7 on the MSI board), a brand new MSI K9AG Mobo with an Athlon X2 and a Fujitsu Siemens Amilo notebook with an Intel Pentium M. The only system that works is the Asus, which runs SuSE 10.0 with a special kernel, the other two run Ubuntu Desktop 7.04 (Notebook) amd Ubuntu Server 7.10 (MSI).

I suggest you try it on the same machine with a boot CD.

I'll try with a Knoppix CD and/or a SLES installation CD.

It can also be host software controlled. The device may present a list
of functions and then the software on the host can choose one. I
believe a change was made in the way Linux chooses a function at some
point in order to ensure sufficient power in case all devices
concurrently demanded their worst-case amounts.

Unfortunately, I don't recall enough of the details.

At least, you've pointed me into the right direction. I hope I can pick up there and find the reason.

Thanks and ... best wishes,

Josef
--
These are my personal views and not those of Fujitsu Siemens Computers!
Josef Möllers (Pinguinpfleger bei FSC)
If failure had no penalty success would not be a prize (T. Pratchett)
Company Details: http://www.fujitsu-siemens.com/imprint.html

.

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