[mythtv] RFC: ALSA snd-mixer device for PVR-350 TV-out audio control

[Perry Gilfillan]

I've only recently acquired a couple of Hauppauge cards, a 500 and a 
350, so I'm still getting up to speed on the capabilities of the chip 
sets and drivers, but now that I have X running on tv-out, but no volume 
control ( no sound card to patch through ) I want to see if the ALSA 
snd-tvmixer module I wrote for use with the Voodoo3 3500 TV will work 
with the PVR-350.

The snd-tvmixer source is here: http://www.gilfillan.org/v3tv/ALSA/ but 
may not be quite up to date.

Grab the archive at 
http://gilfillan/v3tv/v3tv-v4l2/tvmixer2615.patch.bz2 for the newest 
release.

The basic operation is to attach to the msp3400 module through the i2c 
bus.  When snd-tvmixer finds an i2c chip that presents a volume control, 
it creates an ALSA mixer device so that tools such as alsamixer can 
twiddle the volume and tone controls.

The V3TV card has an MSP-3430g sound decoder, which has various volume 
and tone controls.

When loading the snd-tvmixer module on the system with the PVR-350 
running, I get this:

  snd-tvmixer: snd_tvmixer_adapters found ivtv i2c driver #0
  snd-tvmixer: Found i2c_client tveeprom
  snd-tvmixer: i2c_client not a Mixer?
  snd-tvmixer: Found i2c_client LG NTSC (TAPE series)
  snd-tvmixer: i2c_client does not have a volume control
  snd-tvmixer: Found i2c_client saa7115
  snd-tvmixer: i2c_client not a Mixer?
  snd-tvmixer: Found i2c_client saa7127
  snd-tvmixer: i2c_client not a Mixer?
* snd-tvmixer: Found i2c_client MSP4448G-A2
* snd-tvmixer: MSP4448G-A2 (ivtv i2c driver #0) registered
  snd-tvmixer: Found i2c_client tda9887
  snd-tvmixer: i2c_client does not have a volume control


It does find the MSP4448G-A2 and creates a mixer device. At this time 
alsamixer draws the various controls, but they have no effect.


I'll go get that datasheet and see if I can wrap my brain around the 
problem.

Cheers,

Perry