Changing PCMCIA IRQ
jimc at math.ucla.edu
Fri Apr 19 16:07:47 EST 2002
Some time ago I reported having problems with a Dell TrueMobile 1150
802.11b mini-PCI card (in a Dell Inspiron 4100 running orinoco_cs and
friends v0.10) (and yes I'll install v0.11 this weekend), talking to a
Linksys WPC11 in a Linksys PLX interface (can't remember the part number)
with the same driver version.
The symptom is very slow data transfer when transmitting out of the Dell
card, and "excessive Tx retries" on every packet (within 2% of equality),
which would explain the slowness, particularly since the card falls back to
2 Mb/s. Every packet arrives at least once at the Linksys card, but Rx
counts indicate they arrive three or four times, the extras being
suppressed at the transport level. The Linksys card reports about 5% of
Tx packets having excessive retries (probably because the partner is all
tangled up). Similar slow transmission was seen in WinXP, though detailed
stats were not available. With a Cisco-Aironet access point the same
behavior is seen.
It looked like the card was broken, and I got Dell to replace it. The
symptoms went away in WinXP, but are still there under Linux. My current
hypothesis is that interrupt sharing is not a good idea, since with the
default assignments practically the whole laptop is on IRQ 11: wireless
NIC, wired NIC, sound, probably modem if I had a driver for it, USB host
controller, and the 2 empty PCMCIA slots. On WinXP the wireless NIC, sound
and modem are on IRQ 5, while the others, plus the graphics controller, are
on 11. (XFree86 either doesn't use the IRQ or doesn't register it.) My goal
is to shift the wireless card to IRQ 5.
So I edited /etc/pcmcia/orinoco.conf to say:
include irq 5
module "orinoco_cs" opts "irq_list=5"
(And unloaded the modules and restarted Card Services.) But Card Services
still uses IRQ 11 for the wireless mini-PCI card, as shown by "cardctl
config" and in /proc/interrupts. Before I go off to a crusade of "use the
source, Luke", can anyone advise me of the right way to do this?
James F. Carter Voice 310 825 2897 FAX 310 206 6673
UCLA-Mathnet; 6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA 90095-1555
Email: jimc at math.ucla.edu http://www.math.ucla.edu/~jimc (q.v. for PGP key)
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