[LinuxBIOS] #57: libusb host program for PLX NET20DC debug device

Eric W. Biederman ebiederm at xmission.com
Mon Dec 4 00:03:55 CET 2006

Peter Stuge <stuge-linuxbios at cdy.org> writes:

> On Fri, Dec 01, 2006 at 04:02:03PM -0700, Eric W. Biederman wrote:
>> >> Sure, I will send it out shortly.  I currently have a working
>> >> user space libusb thing (easy, but useful for my debug)
>> >
>> > Hm - for driving which end?
>> Either.  The specific device we are talking about doesn't care.
> Which device do you have?

Well it is built by PLX, and from lsusb I see are:
0525:127a Netchip Technology, Inc. 

The hardware is a little rectangular pcb board a little smaller
then a business card.  Wrapped in a blue case, with vertical vents
on both of the long sides, and gets a little warm when you have been
running it for a while.  The device has what appears to be 2 normal
host to slave cables running into it.

The picture at the bottom of:

Looks like what I have.  I'm curious about the whole plug both
ends into the host before plugging it into the client, and about
the strange target system BIOS requirements.

I think I succeeded in making it work without out that by just putting
in a reset.  It does make the whole setup of the device a pain though.

>> > The debug port isn't really supposed to be used with anything but
>> > a debug device - which can't be enumerated normally anyway.
>> It depends.  If you have a debug cable with magic ends and a
>> hardcoded address of 127 the normal enumeration doesn't work.  I
>> don't think anyone actually makes one of those.
> Only one of the ports on Stefan's PLX NET20DC that I had a look at
> during the LinuxBIOS symposium enumerated for me.

Very odd.  I'm pretty certain we are talking same thing.  But I do
know it has a couple of weird quirks, so maybe you just ran up against

>> Debug devices are also allowed to be normal devices that just
>> support the debug descriptor.  Which is what I'm working with.
> Aye. I would be happy if we could get something out, as you have
> done! :) Looking forward to trying it, I hope I get my device soon.

Well at least this means after it works I can probably forget about
it and let someone else maintain the code ;)


More information about the coreboot mailing list