Re: dabusb/usb modems conflict issue

[David Brownell <david-b@pacbell.net>]

Hi,

> Well.. our driver support a lot of GlobeSpan chipset-based USB ADSL modems,
> and in most cases, hotplug loads dabusb module at startup to add support for
> the (modem) devices.

The URLs you mentioned don't seem available to me just now,
so I can't see any more information than is found in your
email message ...

EVERY version of "dabusb" I've ever seen has a bug in
its MODULE_DEVICE_TABLE entries:  they claim the default
EZ-USB product/vendor IDs.  Those IDs are not supposed
to be used by _any_ product except Cypress devkits.
(Which means any developers working with Cypress EZ-USB
and Linux trip over the bug...)

In fact, the current drivers (2.4, 2.5) seem to have
only two IDs, both with Cypress vendor IDs.  One of
them is a bug, and needs to be removed.  I don't know
about the other one; it could be legit.

Assuming this isn't a hotplug bug, there are exactly
three possibilities:

  - This GlobeSpan driver is also trying to bind to
    default EZ-USB devices.  **BOTH** drivers have bugs,
    since no production devices may use those IDs.

  - Or the globespan driver is also trying to bind
    to the other (pid 9999) device entry.  Assuming
    that ID was allocated legally only one of the
    drivers can possibly be correct.

  - Both drivers are using VID/PID entries they aren't
    allowed to use, for the second entry (the one that's
    not the EZ-USB default).  For example, that ID may
    not have been allocated to either one by Cypress.

Do you know which is the situation?


> We used to disable dabusb module load by removing the module file or
> re-configuring the kernel to skip dabusb support, and with latest versions of
> hotplug (depending on the GNU/Linux distro), we recommend our users to add
> dabusb to the blacklist file.
> 
> 
> You will find related info about how we manage this issue there:
> 
> the project page..
> http://eciadsl.flashtux.org/index.php?lang=en
> 
> the supported modems list (including vid/pid)..
> http://eciadsl.flashtux.org/modems.php?lang=en
> 
> our Q/A in the FAQ related to this dabusb issue..
> http://eciadsl.flashtux.org/faq.php?lang=en#2.1
> 
> 
> My questions:
> 1/
> Do we use the right method to avoid dabusb loading for non-audio-dabusb
> devices (modems).
> 
> 2/
> Is this really a conflict? What's your thought about this?
> 
> 3/
> Do you have any piece of advice related to this (generally)?

The blacklist exists basically to cope with driver bugs,
you should find out what the situation is.  Does your modem
driver include product/vendor IDs for pre-production units?
If so, just remove them.

- Dave


> 
> Thanx in advance,
> regards
> 





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