I had this problem. I have fixed it, and am documenting the procedure here so for the benefit of anyone having this problem.
After an update on my muthbuntu box which included a kernel update from 2.6.24-16 to 2.6.24-18, the dvico "dual digital 4" dtv devices stopped working. I was using a
v4l tree provided by Christopher Pascoe.
Of course, the solution should have been simple - the v4l drivers needed to be rebuilt. But a make clean; make; sudo make install didn't fix the problem. Cue extensive troubleshooting.
To cut a long story short, the make clean target in the v4l tree is broken. It leaves various generated configuration files in place, which prevents the tree from correctly building for the new kernel.
My solution was to re-do the clone from mercurial. Diffing the new and old trees gave me the following output - deleting the mentioned files (apart from the .dirstat file, of course) may well work, but I am not about to risk breaking my machine to test.
Code:
~$ diff -r xc-test.1 xc-test
Binary files xc-test.1/.hg/dirstate and xc-test/.hg/dirstate differ
Only in xc-test.1/v4l: .config
Only in xc-test.1/v4l: Kconfig
Only in xc-test.1/v4l: .kconfig.dep
Only in xc-test.1/v4l: Kconfig.kern
Only in xc-test.1/v4l: Makefile.media
Only in xc-test.1/v4l: .myconfig
Only in xc-test.1/v4l: oss
Only in xc-test.1/v4l: .tmp_versions
Only in xc-test.1/v4l: .version
To help yourself in future, take of copy of your v4l tree (cp -r dirname dirname.build) and build in that copy. That will leave your original tree clean for when you need to rebuild.