[mythtv-users] Kernel 4.18 regression with some tuners

Adam Stylinski kungfujesus06 at gmail.com
Mon Sep 10 14:18:31 UTC 2018

On Sat, Sep 08, 2018 at 07:23:02PM -0400, Devin Heitmueller wrote:
> > I recently upgraded from kernel 4.17.1 to 4.18.6 and found out that I could no longer tune to any channels.  The channel scan in the mythtv-setup program would give me a non-sense error when trying to tune (it'd read "Cannot measure Signal Strength" and the error message was unknown error 254).  I was convinced that somehow all 3 of my PC HDTV 5500 PCI tuners had finally died, or something goofy was happening on my PCI controller with interrupts.  After playing around long enough, I decided to downgrade to an older but still supported kernel (4.17.19).  After that, I was able to tune to channels like before.  What tipped me off was this bug report filed from another consume of media devices in the kernel:
> > https://tvheadend.org/issues/5183
> The patch mentioned in this tvheadend issue is entirely an internal
> API change (how the core interacts with the demodulators) - it should
> have no effect on the userland API.  Further, even if the units were
> off, it wouldn't result in a 254 error code.  I think the user was
> just taking a stab in the dark based on looking at the changelog, not
> based on actually bisecting the kernel.
> > That seems to indicate the exact git revision where the regression occurred.  Has anyone else had issues with this kernel and know if and what details should be included in a post to LKML for this regression?
> Any such issue should be reported to the linux-media mailing list, not
> linux-kernel:
> linux-media at vger.kernel.org
> Devin
> -- 
> Devin J. Heitmueller - Kernel Labs
> http://www.kernellabs.com
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Hmm, I emailed them but haven't seen much of a response yet:

Admittedly, the email had a couple of typos (I sent it while rushing out of the house).  Still, oddly silent.
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