Bug#527963: Regression bug - xirc2ps_cs kernel module works under Etch, fails under Lenny
When I closed this bug report, it appeared that my Compaq Netelligent
10/100 PC Card Ethernet adapter WOULD work with Ethernet cables which
have no soft plastic boot protecting the hard plastic hook, but WOULD
NOT work with cables which have boots. Subsequent testing, however,
has disproved this. I've found cables with boots that work, and I've
found cables without boots that don't work. I've done quite a bit
of testing since then, and I now believe that the problem is a
combination of cable length and router/switch quality.
When attaching the dongle directly to my home router, which is a
Trendnet TW100-S4W1CA 4-port Cable/DSL Broadband Router, via a single
length of cable, I have found that the card works fine with shorter
cables, such as ten-foot lengths, regardless of whether the cable has
boots or not. The amber "link integrity" light on the dongle comes
on and remains on. When using longer cables, such as 25-foot lengths,
the card does not work. The amber "link integrity" light on the dongle
flashes on and off. This is true regardless of whether the cable has
boots on its plugs to protect the hooks or not.
On the other hand, when I take the machine into the office and attach
the dongle to the wall jack, behind which is a commercial-grade
switch, I can use the longer 25-foot cables successfully, whether they
have boots on them or not.
My current theory is that the Compaq Netelligent 10/100 PC Card
Ethernet adapter draws a lot of current from the router or switch
that it is connected to, in comparison to other PC Card Ethernet
adapters, and that the voltage drop across the longer cables is enough
to make the voltage "out of spec" as seen by the card when it is
connected to my cheap home router. When it is connected to a
commercial-grade switch, which has a lower internal resistance, the
voltage drop is not sufficient to make the voltage "out of spec",
even with the longer cables, and the card therefore works fine.
But that is just a guess. What I do know is (1) when using my home
router, 10-foot cables work with the card and 25-foot cables do not
work with the card, boots or no boots. (2) When using a 3Com card
that I have, either length of cable works fine with my home router,
boots or no boots. (3) When using a commercial grade switch at the
office, both 10- and 25-foot cables work fine with the Compaq card,
boots or no boots. They also work with the 3Com card.
In any case, my difficulties with the card are not related to
changes made to the xirc2ps_cs driver between kernel releases 2.6.18
and 2.6.26.
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