For quite some time, there have been users complaining of DVB-T scanning problems using application such as MythTV or w_scan. Even stranger, they claimed that using /usr/bin/scan would indeed work as expected.
For example, this Launchpad ticket has tracked the issue for almost two years:
MythTV has a ticket tracking the issue too (although closed due to it being declared “upstream”):
I finally got my hands on some hardware to test with, and what I found was not a device specific bug, but rather a race condition in the framework. This will actually effect far more devices than just the three noted above. Pretty much any card which strobes the reset pin in it’s ts_ctrl() function will hit this issue with applications like MythTV.
I’ve cooked up a patch for the issue and submitted it to the linux-media mailing list for upstream inclusion. It can also be found here if users want to apply it directly to a media_build tree themselves:
My hope is that this should fix a longstanding issue where no developer had the time to investigate. I’ve tested it with my DVB-T generator and now I can see that w_scan does work. But it would be great it some users would try it out and report back as to whether it improves their situations. Feedback in the comments section welcome below….