[linux-elitists] Elan Digital Systems devices...

Greg KH greg@kroah.com
Thu Dec 11 12:33:12 PST 2008


On Thu, Dec 11, 2008 at 01:38:09PM -0500, Greg Folkert wrote:
> Ok, now I have something not supported that probably should be able to
> be supported fairly easily.

More details below why this is not the case...

> I have an Elan Digital Systems U142
> http://www.elandigitalsystems.com/adapter/u142.php
> 
> Re-badged as Quatech PCX-D/U142-E that I purchased it from here:
> http://sewelldirect.com/U142-USB-to-Cardbus-Adapter-for-3G-High-Speed-Modem-PCMCIA-Cards.asp
> 
> This is one of those things I need to use for my netbook to extend
> capability. I have a EEE-PC 2GB Surf with 512MB and 2GB SSD all soldered
> on. I have a 4GB SDHD Memory card for it and this Elan device for my
> AC595.
> 
> I'll send one of these off to someone for free to get it able to be
> usable for Linux. I just need a guarantee that the certain person will
> work on it.
> 
> This device works with the WindowsXP version and my AC595 perfectly
> through Verizon.
> 
> I've will attach the output from "lsusb -vvv -d0403:6deb" and all the
> logs relating to the HAL and message and debug stuff I can find, if you
> want it for direct send off list.

Greg sent me the logs off-list and they confirmed my first guess.

Namely, stay away from crap hardware like this.  Oh, and Linux also
doesn't support it either, probably because any developer who sent in
patches for it would be laughed at...

Here's why.

This is really a USB to PCI adapter.  We started to see these get
developed around the time that the ExpressCard standard was being
created, back when it was only going to be a USB connection.  The
standard committee finally relented, and now it's also PCI express as
well as USB (but not both at the same time, that would just confused
people even more...)  So companies started to create a USB to PCI bridge
chip thinking that they were going to make a lot of money selling them
to the current cardbus vendors so that they could keep alive their
existing designs by just adding on an additional chip.

In the end, sanity reined, thankfully.

Now it looks like a batch of these chips are being used in the above
mentioned devices in order to try to provide network connectivity using
old, out of date, cardbus modem cards.  But it turns out that these
cardbus modem cards are themselves just a USB host controller with a
simple usb to serial device to connect up to the modem.

So, when you hook all of this up together, you get the following chain
of hardware lunacy:

  computer -- PCI -- USB host  -- USB root -- USB   -- USB to   -- PCI -- USB host  -- USB root -- USB    -- cellular
              bus    controller   hub         device   PCI bridge  bus    controller   hub         device    modem

Now if that doesn't look like a system ripe for laughing at, I don't
know what is.

Just go get one of the many USB cellular modem devices out there on the
market today.  They are dirt cheap, and take about 4 layers out of the
system, making everything go faster in the end.

Note, wireless USB hubs look almost like the above chain-of-mess, which
is one reason I would never recommend them for anyone, it was the result
of a horrible "design by committee without every having implemented the
spec before we ratify it" system.

Oh, and to top it all off, the above mentioned device looks like it is
USB 1.1 only, able to send 40bytes at a time maximum.  Not something
that I would expect would perform well under any type of modern
networking expectations.

Heh, thanks for making my day, this is a really funny device...

greg k-h


More information about the linux-elitists mailing list