I have been workiing on this for about 2 weeks now, and still havent solved it. I had an FC2 install with a working MythTV Setup with a Hauppauge PVR-250. Remote worked also.
I installed FC4 on a seperate drive, but left FC2 on the other drive. I am trying to get Myth working on the FC4 drive. I can load all the modules and the remote works fine, but all I seem to get is snow. I have went over the settings with a fine tooth comb, but still no luck. The weird thing is if I boot into FC2 and use Myth, then boot into FC4, Myth will work, but only on 1 channel, if I try to change the channel, it seems like it is changing, because the OSD changes, but the same channel shows. I have compared the settings with my FC2 installation and they appear to be identical.
I dont see any errors in /var/log/messages in the ivtv section, it seems to be just about the same as what I see in FC2. In FC2, when I start mythbackend, it loads all the modules I need (ivtv, saa7115, etc). In FC4, I have to manually modprobe them.
I tried compiling ivtv myself this morning, after removing it with yumex, but I got an error in saa7115...line 1139. In FC2, I did manually compile and install ivtv.
I could attach var/log/messages, the results of lsmod, etc if need be.
If anyone has any ideas, I would appreciate it. Thanks!