Re: PPP with PCMCIA modem stalls on 2.6.10 or later

[Kouji Toriatama <toriatama@inter7.jp>]

Paul Fulghum <paulkf@microgate.com> wrote:
  > Try the following patch, and report the syslog output.
  > 
  > This may be lost receive data due to full flip buffer.
  > 2.6.9 would try processing rx data in the ISR if the
  > flip buffer was full. This violated locking requirements
  > and was changed to only process rx data in scheduled work.
  > This can slow the processing of data.

I have tried your patch.  The following is a part of syslog
output.
------------------------------------------------------------------
Feb 16 23:52:40 moka kernel: receive_chars:flip full:low_latency=0
Feb 16 23:52:40 moka kernel: receive_chars:flip full:discard char
------------------------------------------------------------------
I have got this pair of two lines many times while running the
wget command.


  > Also try using the setserial utility to set
  > the 'low_latency' option for the device. That should
  > operate the same as 2.6.9 (which can be dangerous).

With 'low_latency' option in 2.6.15 with your patch, the problem
did not occur and no output from syslog.


  > The improved flip buffering code in 2.6.16-rc3
  > should also prevent any loss of data. If possible,
  > try 2.6.16-rc3.

I have tried 2.6.16-rc3.  With or without 'low_latency' option,
the problem did not occur.  It seems to work fine!  I will use
2.6.16-rc3 or later.

If you have any additional plan to pin down this problem, I will
try your patch.


Thank you for your help,
Kouji Toriatama