Tvheadend

I have this card and I have never seen that particular issue. I would suggest you use the standard TBS drivers, since they are known to work with this card. You have to rebuild them every time there is a kernel update, and there is a script to do that at https://freetoairamerica.wordpress.com/2015/12/22/a-bash-script-to-rebuild-the-tbs-tuner-drivers-after-linux-kernel-updates/

The TBS drivers are at http://www.tbsdtv.com/download/ but the script mentioned above should make installation easier, however there's no reason you can't install the drivers manually if you enjoy doing that sort of thing.

Alternately if you are a real Linux guru then you might want to try updatelee's kernel at https://bitbucket.org/updatelee/v4l-updatelee but I can't give you any real advice on that because I'm not that much of a Linux expert. You may want to do a search to gather information on "v4l-updatelee" if you are going to attempt this. I would suggest you try the standard TBS drivers first, though. You may need to first uninstall the CrazyCat drivers before the TBS drivers will function correctly, and again I can't tell you how to do that - I would personally just rebuild the entire system from scratch to make sure I have a "clean" install, but that's just me.

Also you did not mention which version of TVHeadEnd you are running, I have version 4.0.9 from the stable branch, don't know if that might make any difference.

I use latest trunk version of TVH, anyway this seems unrelated to TVH as this error is thrown by kernel itself.
Dunno what updatelee's kernel is, but I prefer to stick with hardened one, supporting PaX and GrSec.
I will try the drivers from TBS. Thanks!

updatelee kernel adds extended capabilities for STV demod devices like TBS 5925 5980 6925 6983 for spectrum scanning and IQ Plot.

For TMAX device like 6985 it has Luis Alves driver.