[mythtv-users] Workarounds for multiple HVR-950Q not tuning

Devin Heitmueller dheitmueller at kernellabs.com
Sun Jan 31 19:20:45 UTC 2010

On Sun, Jan 31, 2010 at 12:23 PM, Andrew Cagney <andrew.cagney at gmail.com> wrote:
> Hi,
> I've also hit the problem described in "multiple HVR-950Q usb tuners"
> (http://mythtv.org/pipermail/mythtv-users/2009-November/269626.html)
> where one of the tuners may not work after a power-cycle (both inside
> or outside of mythtv so a driver problem).  The symptom I see is
> "Partial Lock" when attempting to use live-tv.
> The h/w is Acer Revo R1600 and OS is:
>  Linux tv-desktop 2.6.31-17-generic #54-Ubuntu SMP Thu Dec 10
> 17:01:44 UTC 2009 x86_64 GNU/Linux
> Poking at I've found that both the below seem to get past the problem:
> - Powercycle just the tuners vis:
>  - stop mythtv's backend
>  - unplug both tuners
>  - plug both tuners back in
>  - start mythtv's backend
>  (since all this takes time, it points to a race condition)
> - delay the driver's load until after the machine is up vis:
>  - add "blacklist au0828" to a file in /etc/modprobe.d/
>  - edit /etc/init/mythtv-backend.conf's "script" section to read like:
>        date > /tmp/au0828.log 2>&1
>        sleep 10
>        modprobe -v au0828 >> /tmp/au0828.log 2>&1
>        sleep 10
>        exec /bin/su -c "/usr/bin/mythbackend $ARGS" $USER
>  (which is more automated)
> Any one know if this was reported upstream, if not I guess I post
> something more detailed to linux-media at .

Hello Andrew,

Well, in this case I actually track both linux-media and mythtv-users,
so while normally I would direct such a question to linux-media (since
it clearly looks like a driver issue), in this case I'll just step in
and offer a response since I'm the maintainer for the driver in

At this point, I have a couple of sample boards but haven't actually
tried them both at the same time.  It's on my todo list, although
right now I've been tied up with other things and haven't worked on
the 950q recently.  I suspect more debugging needs to be added to the
driver, so we can see where the race is coming from (and whether the
issue is with the bridge, demod, or tuner).


Devin J. Heitmueller - Kernel Labs

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