[linux-dvb] Tuner not detected on second Kworld card

David Engel david at istwok.net
Sun Oct 14 17:32:43 CEST 2007

On Thu, Oct 11, 2007 at 01:46:32PM -0500, David Engel wrote:
> Notice the absence of an equivalent "tuner 1-0061: chip found" line
> for saa7133[1].  This occurs with both the 2.6.21 and 2.6.22.*
> kernels.  I briefly tested analog and digital capture on both cards in
> a separate system before installing them in the MythTV backend so I
> don't suspect a hardware problem.
> Not being able to tune could explain not being able to to an analog
> capture.  Could this be another case of probing being done by the
> various drivers causing problems?  If so, has any of it been fixed in
> the recently released 2.6.23 kernel?  I've already had to go back to
> the 2.6.21 series on this system because the probing caused a minor
> problem with the Hauppauge cards.

I tried moving the Kworld ATSC 115 cards around and also removing one
at a time to see what would happen.  I confirmed the tuner could be
detected on each Kworld card in some configurations so I don't think
it's a hardware problem with the Kworld cards themselves.  I also
found a case where the tuner on a Kworld card would only be detected
if I blacklisted the ivtv driver to make the system ignore the
Hauppauge cards.  Both Kworld cards are now in slots where the tuner
was detected individually in one form or another, but the driver still
won't detect the tuner on both Kworld cards.  It always only detects
the first one.

While I can't completely rule out a motherboard or BIOS problem, it
does look like a probing/detection problem with the cx88 and/or ivtv
drivers.  Are any of the fixes for that in the 2.6.23 kernel yet?

> The minor problem I mentioned earlier has to do with using the
> saa7134-alsa module to capture sound directly from the card.  A quick
> glance at the driver source code looks like it shold support 32 and 48
> kHz sampling rates.  I've only been able to get 32 kHz working well so
> far with MythTV.  Trying 48 kHz results in some sort of rate mismatch.
> Is 48 kHz supposed to work?

I tried using mplayer with 48 kHz audio and got the same results.
Regardless of the requested audio rate, the cx88-alsa driver or
hardware only supplies 32 kHz audio.  The result is audio underruns
and chipmunk audio because the samples that are received are being
played too fast.  Can anyone confirm the Kworld card can only do 32

David Engel
david at istwok.net

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