I'm also getting this error message:
ddbridge 0000:02:00.0: Frontend requested software zigzag, but didn't set the frequency step size
I'm running 6.10.0-rc5 with two Digital Devices adapters. I know that it's only an RC so it won't be looked at now, but I'd like to share with anyone experiencing the same issue.
I did not have any error messages in 6.9.2. The adapters still work in TVHeadend but the logs are filling up quickly. A log entry every second. While I'm getting this error message the DVB info box is empty. A reboot does not help in my case. I have to first go to the DVB settings and select another DVB package and then select DigitalDevices again, click on the update button. Then I reboot and the DVB info box lists my adapters and no more errors in the log. This error comes back after a while. Not sure what sets it off.