Re: PCMCIA/PPP/MODEM problems
> Hi, I'm experiencing a strange problem with ppp and my pcmcia modem.
> I have no problems receiving data, surfing the web or downloading, but when
> I try to send an email bigger than 5k, the connection stops.
> I had this problem with the 2.3.5 ppp package with slink and 2.0.36. Then I
> upgraded the kernel to 2.2.12, and i got TCGETATTR(...): input/output error.
> I upgraded gcc to the potato version and libc6 to 2.1. I downloaded
> ppp-2.3.11.It didn't worked in any sense, nor with 2.0.36 neither with 2.2.12
> 18:49:43 beck pppd[485]: sent [LCP EchoReq id=0x7 magic=0x8d2bb16b]
> (the same TCGETATTR(..)). It's really annoying, I can't reliably send e-mail
> without having the doubt it would be lost.
I have been having exactly the same trouble - I can download fine, but
uploading
even a few kilobytes causes my Billionton FM56 pcmcia modem to hang (I
have to
kill pppd and wait a long time for it to come back). If you wait long
enough
you see lcp echo timeouts and serial ioctl failures. Typically I can
upload about
1-2 kilobytes, then I get a single RX error and I'm stuck.
I have had the problem with both slink and potato (which I am now
running) on a
Sony PCG-N505X and a unbranded Celeron Laptop, and I have done a few
experiments to
isolate the cause:
(1) Changing the IRQ or memory address assigned to the modem makes no
difference,
nor does using htwtools to set IRQ priority. I've tried from irqs
from 3-15.
(2) The problem seems to occur on the stable 2.2.14 kernel and on all
pre-release
2.2.15pre7-17 kernels.
(3) I tarred my Debian installation across onto a collegues laptop
(completely different modem to mine), and found that whilst my
pcmcia modem
hangs on upload the same as my machine, his lucent winmodem (using
the ltmodem.o module) works fine - interestingly they both use pppd,
but the winmodem uses
neither pcmcia-cs OR the kernel serial module.
(4) Using all kinds of AT commands to force the maximum connect speed
down, to
prevent using V90 and use V34 etc etc seem to make no difference
whatsoever.
(4) My modem also works fine in windows and indeed in a macintosh laptop
using
generic drivers.
You *can* work around the problem by doing:
setserial /dev/modem irq 0
to cause the kernel to stop using interrupts and use a slower polling
mode, however
this gives a maximum data rate of about 19 kbits-per-sec on my machine
):
Since the collegues winmodem works, I conclude that pppd is probably OK;
it therefore has to be a fault in pcmcia-cs or the kernel serial module
(or its my
fault (: !).
Any thoughts would be appreciated, please CC to simon@dcs.qmw.ac.uk as I
am not
subscribed to this particular list right now.
Cheers,
Simon
--
Simon A. Boggis Systems Programmer
Department of Computer Science,
Queen Mary and Westfield College London, E1 4NS, UK. Tel. 020 7882
5234
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