[pvrusb2] Problems with HVR 1950

[Mike Isely]

On Tue, 30 Mar 2010, Blake Campbell wrote:

> Hello Mike,
> 
> I'm working with Edmundo on this project and wanted to follow up with our
> previous post.  I was able to modify the udev rules as you suggested, and
> now on bootup the video nodes all mount with the correct permissions and
> ownership.  I accomplished this by adding the following line to
> "/lib/udev/rules.d/41-mythtv-permissions.rules":
> KERNEL=="video[0-2]", OWNER="paradise", MODE="0777"

Yeah, that would do it.  If the mythtv backend is actually running under 
the user "paradise" then I suggest you modify the MODE to be 0660 
instead (no reason to allow anyone access to those device nodes).


> 
> However, despite these permissions, the MythTV frontends still give this
> error after a reboot: "Error: MythTV is using all inputs, but there are no
> active recordings?"

That sounds like a different sort of problem...


> 
> The only way we've found to get the frontends to work is to manually stop
> and then start mythtv-backend from a terminal or script.  I'm not sure if
> it's related, but I have noticed that the video devices don't appear as
> /dev/video[0-2] until maybe 10 or 20 seconds after the desktop appears.
> Could it be that the MythTV backend is initially loading before the usb
> video devices are mounted by the system, and that's why stopping and
> starting the backend fixes the problem?
> 
> We are grateful for any ideas you might have.

Well we're getting kind of off into left field here.  This is likely a 
mythtv issue not so much a driver issue.  But it helps to remember a few 
things about the HVR-1950: It's a hybrid device.  And by hybrid I mean 
that it has separate digital and analog tuners.  However they both share 
the same video pathway so you can only use one at a time.  The digital 
tuner is handled via the DVB interface while the analog tuner (and the 
composite & s-video inputs) is handled by the V4L interface.  This means 
that is something for example has the DVB interface open an active then 
the V4L interface won't be usable.  Same is true the other way: the DVB 
interface can't be used if the V4L interface is active.  The pvrusb2 
driver enforces this exclusion internally so there's no risk of 
"screwing anything up".  But the error you hit might be due to that 
"other" interface being open.

And I've read elsewhere that if you enable EPG scanning on the DVB 
side, then mythtv will at various times open the DVB interface to do its 
electronic program guide scanning - but this action is not kept 
coordinated with the V4L side and thus errors can happen.  So the 
summary here is to see if you have EPG scanning enabled and if so, 
disable it...


-- 

Mike Isely
isely @ isely (dot) net
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