[Asterisk-Users] Re: Problems with TDM400P card

[Andrew Kohlsmith]

On May 5, 2005 12:01 am, Mike Mueller wrote:
> I am new to Asterisk, but so far, having looked at this thread (which is
> quite long and full of lot's of hard work), the zttest code, the Digium web
> site, and the spandsp website, and having talked to Digium sales/support
> about the TDM, I think the issue belongs the spandsp community.  They may
> be able to point out an improvement to the TDM product that Digium may or
> may not implement.  Or they may need to adapt to an improvement on new TDM
> cards. It does not appear that Digium has promised support to
> the spandsp add-on function to Asterisk. I also didn't see where the
> spandsp project was committed to staying up to date with each new revision
> of TDM card - that's what the community is for.

We're not asking Digium to support spandsp, it's just an application that 
really exhibits this problem.

My two fax machines (Canon IR3300 and Panasonic something-or-other) do not 
work with the TDM400P either on fax reception; fax transmission works fine.  
This is most certainly a TDM400P driver issue.

Couple this with the fact that the driver now seems to pull 100% CPU every 5 
seconds or so and it didn't before and I think we have a good case for there 
being something weird in the driver that is causing frame slips or other 
weirdness that is generally not audible for most people but wreaks havoc even 
for G3 or ECM (I think that's the term for error-correcting fax) fax 
machines.

> In summary, it doesn't appear that spandsp not working and zttest output
> is sufficient to cast doubt on the TDM cards.  More comparison between
> working and non-working spandsp faxing apps might give more reliable
> clues about where the problem lies.

Nah; we've been down this road.  I just need a block of time to pull wctdm 
from about a year back and basically do a binary search until I find where 
the driver started pulling this insane CPU use every 5 seconds or so.

You comments on zttest and kernel process scheduler are very important, IMO.   
I don't know, I think Digium made a horrible mistake by not including even a 
small buffer on these cards.

-A.