[pvrusb2] pvrusb2 and Fedora 11 - Audio cut after sometime of capturing

[Mike Isely]

On Tue, 18 Aug 2009, Alejandro Vaquero wrote:

> I tried a couple different vanilla kernels from kernel.org, but so far no
> improvement. Here the kernels installed:

>   kernel 2.6.30.4: Could not boot the machine with this one (got some kernel
> panic message)
>   kernel 2.6.27.29: Could not boot the machine with this one either.

There might need to be a module in your initrd that you need here.  Just 
guessing (having been down that road before).


>   kernel 2.6.29.6: Machine works fine but still have the same issue (audio cut
> after some time while capturing from 29xxx) . This is the same issue as
> running the F11 kernel 2.6.29.6-213.fc11.i686.PAE

OK, so this is an important clue.  You're running a vanilla kernel and 
still you have the audio problem.  That rules out Fedora-introduced 
issues into the kernel.


> 
>    Here the procedure used to compile the vanilla kernels (in case I'm doing
> something wrong):
>   1- copied the F11 kernel config to my kernel source dir:
>          # cp /boot/config-2.6.29.6-213.fc11.i686.PAE .config
>   2- Run
>          # make oldconfig
>       This asked a couple of questions depending which kernel was compiling. I
> choose all defaults.
>   3- Compile and install the kernel:
>          # make
>          # make modules_install
>          # make install

That's a good first cut; it's what I would have done.

As for the underlying problem...

Once the device is streaming there really isn't much else for the 
pvrusb2 driver to do except to keep shoveling the bits that come out of 
the hardware.  It's worth noting here that when I say "bits" what I mean 
is the final mpeg stream from the hardware - after the audio and video 
subchannels have been combined by that hardware.  Thus if the audio 
"stops" yet the video keeps on going there's not a lot that the pvrusb2 
driver itself could be doing to cause this.

I re-read your original description and one of the things you mentioned 
is that you have both a 29xxx and a 24xxx device but the problem only 
happens on the 29xxx device.  That is another interesting datapoint.  
The hardware is different in the two cases, but the meaningful 
differences as far as audio is concerned involves the sub-device driver 
used by the pvrusb2 driver and not the pvrusb2 driver itself (mostly).  
Your 24xxx device uses a cx25840 type of part to process both the audio 
and the video (into a form that the cx24116 mpeg encoder requires).  
Your 29xxx device uses an msp3400 type of part to instead process just 
the audio (an saa7115 does the video side).  The way the pvrusb2 driver 
handles all of this really comes down to just selecting and setting up 
the sub-device driver.  Once set up, the pvrusb2 driver sends the same 
V4L commands to that driver, regardless of which one it is.

So, if your 24xxx works but the 29xxx does not, then I'd suspect that 
either your 29xxx device has a hardware problem, or that the msp3400 V4L 
driver (msp3400.ko) is having a problem.  However you said this all 
works in F10 so that would rule out a hardware problem with the 29xxx 
device.  Very likely there are changes in the msp3400 driver included in 
the different kernels with those Fedora releases.

With the additional evidence that you managed to reproduce the problem 
with a vanilla 2.6.29 kernel, that's something I should be able test for 
here.  Most of the development work I've been doing has been under 
2.6.27.x as of late.  However I've jumped into 2.6.29.x a few times to 
test changes that I know only come into play there.  I haven't beat on 
that kernel a lot (mainly because I've had another unrelated problem 
with that kernel version which nearly wrecked my root file system so 
I've been loath to do a lot of testing there).  In particular I probably 
haven't done enough testing with that kernel on a 29xxx device.  But now 
that you're seeing a problem that I should be able to reproduce I'll 
give it a try and let you know if I find something.

  -Mike

-- 

Mike Isely
isely @ isely (dot) net
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