[pvrusb2] mythtv and wintv-hvr-1950 - analog/digital scanning

[Mike Isely]

On Tue, 6 Jan 2009, fivenote wrote:

> OK... keeping things simple... :-)
> 
> as root...
> 
> * mythbackend off
> 
> * plug in HVR-1950, creates /dev/video0
> 
> * enum_val shows all inputs - no narrowing
> 
> * set cur_val to composite and attache video player to hvr-1950
> 
> * cat /dev/video0 > /tmp/foo
>        stderr...
>            cat: /dev/video0: Input/output error
>        /tmp/foo...
>            empty
>        /var/log/syslog...
>            Jan  6 21:00:39 vao1420 kernel: [ 3031.735288] pvrusb2:
> WARNING: No decoder present

Bingo.  Why I didn't ask you to look at the log before is beyond me :-(  
D'Oh.

That warning is happening because the video digitizer / decoder 
chip-level driver has not attached itself to the pvrusb2 driver.  This 
is one of those other bits of v4l-dvb needed for the pvrusb2 driver to 
operate, and in this case that driver is apparently missing.  The driver 
is the cx25840 module, which handles the cx25843 chip in your device.  
This is the part that converts the incoming analog video signal into a 
frame buffer (which is then passed to the cx23417 chip for compression 
into an mpeg stream).  Without control of that chip, the video pipeline 
can't run.  The driver is detecting this, spitting out the message and 
killing the stream.  I don't think anyone's hit that behavior before, 
which is why I didn't expect it.  But the system log tells all.

But wait - in your other reply you posted a large log snippet and the 
cx25840 messages were all there.  If you do an "lsmod" do you see the 
name cx25840 in the resulting list?  Another thing you can try: In the 
sysfs interface there's a node called "debuginfo".  If you read that 
(i.e. 'cat /sys/pvrusb2/*/debuginfo') you'll get a dump of the list of 
attached chip-level drivers.  Within that list you should hopefully see 
something like this:

  handler: pvrusb2-cx2584x-v4l

Do you see that?  Also, when you cat out debuginfo, this implicitly 
triggers a request to all those drivers to dump their states into the 
system log.  So if you follow that cat command with a dmesg you should 
see information reported directly by each driver.

I wonder if cx25840 might be failing due to missing firmware?...

  -Mike


-- 

Mike Isely
isely @ pobox (dot) com
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