[pvrusb2] recent problem: getting frontend status failed

[A. F. Cano]

Hi,

I have been running the OnAir Creator for quite a while now and it only
failed (Mythtv) sporadically.  Now, it is a daily occurrence.  I know
there have been recent kernel upgrades (I'm running wheezy) and there
has long been some race condition in pvrusb2 and/or the OnAir Creator
firmware, per some documentation I remember reading.  Not sure if anything
has changed in pvrusb2 in these recent kernel upgrades.

I've failed to definitely confirm whether high loads increase this
problem (such as when doing a transcode) while myth is running.  It
fails even when not much else is going on in the system.  When it does,
killing/restarting myth (FE and BE) is not sufficient.  I have to unplug
the usb plug from the computer and re-plug it.  After this is done,
restarting the BE and then the FE usually, but not always, brings everything
back to normal: myth starts doing the EIT scans and the first show set
to record usually is recorded correctly.  Sometimes subsequent shows are
also recorded ok, but usually not.  Something happens in the interaction
between the Myth backend and pvrusb2.  The following messages appear when
the lock-ups occur.  Many of them.


2014-06-02 17:15:23.748811 E  DVBChan(1:/dev/dvb/adapter0/frontend0): Getting Frontend status failed.
                        eno: Input/output error (5)
2014-06-02 17:15:23.799434 E  DVBChan(1:/dev/dvb/adapter0/frontend0): Getting Frontend status failed.
                        eno: Input/output error (5)
2014-06-02 17:15:23.849978 E  DVBChan(1:/dev/dvb/adapter0/frontend0): Getting Frontend status failed.
                        eno: Input/output error (5)
2014-06-02 17:15:23.900612 E  DVBChan(1:/dev/dvb/adapter0/frontend0): Getting Frontend status failed.
                        eno: Input/output error (5)
2014-06-02 17:15:23.951171 E  DVBChan(1:/dev/dvb/adapter0/frontend0): Getting Frontend status failed.
                        eno: Input/output error (5)

When this happens, attempting to watch live tv gets hundreds of these
messages, Myth claims a signal strength of 0 and pops up a window saying
I should have a signal by now.

This is a relatively slow system (1.4 GHz pentium M) but recording
barely causes the CPU monitor to go to 10% and the CPU is at 800 MHz.
This seems to indicate that it's not a load issue.  But it's probably
a timing problem of some kind, possibly made worse by a recent change?

If this is a mythtv issue, it appears to be cascading into pvrusb2 as
only a usb restart fixes it.  Does anyone have a suggestion? Any
specific tests I can run to narrow this down further?

I also still can't run zone minder from the camera attached to the OnAir
Creator.  The newer kernels have not fixed the problem originally
discussed in a message to this list with the title:

  V4L2_CAP_STREAMING, zoneminder, motion.

Thanks for any hints/help!

Augustine