[linux-dvb] kernel reboot needed after unplugging dvb-t usb in use.

Alan Chandler alan at chandlerfamily.org.uk
Sun Sep 10 18:08:29 CEST 2006

On Sunday 10 September 2006 15:47, Patrick Boettcher wrote:
> On Sat, 9 Sep 2006, Alan Chandler wrote:
> > On Saturday 09 September 2006 08:22, Alan Chandler wrote:
> > ...
> >
> > > Now that everything is more stable, I have been able to experience this
> > > problem in more controlled conditions and it appears to be related to
> > > some form of race condition where the /dev/dvb/adapterN disappears
> > > whilst it is being used.  At least the action that caused the problem
> > > was unplugging the usb connector on the tuner whilst tzap was using it.
> > >  This caused the crash below.

Yes I realised this not long after I posted it, re-reading the documentation. 
I am sorry for the noise on that one

> >
> > Its now happened spontaneously, without unplugging anything.  It may be
> > that the dvb-usb module de-initiallised itself.
> >
> > I have left tzap running for about 3 or 4 hours on in two separate
> > sessions with the two tuners, tuned to different channels.
> 2 Problems here: First the DVB-core is not hotpluggable - that's why you
> get the Oopses. Second something is wrong with your USB, device or host.

Well both devices appear to work fine when plugged in individually, its only 
when they are both plugged in at the same time that they appear to get mixed 
up and cause this to happen.

> That the device sporadically disconnects while being used is an indicator
> for faulty hardware.

The usb driver is reporting -71 errors, which seems to me to be an indication 
of a usb problem.  

I thought it might have been the sticks drawing too much current when plugged 
into the the PCI USB2.0 card I bought for my PC, so I purchased a usb 2.0 
powered hub which has overcurrent protection on each port.  But although 
the -71 errors are much reduced, they still occur (and indeed caused this 
sponteneious disconnect).  This is also true if both are plugged into the USB 
hub, or if one is plugged into the hub (which is then plugged into the card) 
and one is plugged into the card.

I am currently moving the whole configuration over to my desktop machine, as 
its quite difficult to get a clear picture on a headless server.  At least 
now I should be able to look at actual pictures and see what the quality is.

Alan Chandler

More information about the linux-dvb mailing list