https://github.com/raspberrypi/linux/pull/705
Looks like the drivers are slowly being merged into the rpi kernel 3.12.y branch. Pull request #705 has the changes to get the card working. I've compiled using the default raspi config file and installed to a fresh copy of raspian. I've got the card working, but have run into two serious issues that were not present in the unofficial 3.12.yrt kernel that was posted by another member on this site a bit ago. I'm using this card for SDR capture from a softrock-ensemble radio (right now recieve only).
First, positive changes since the patched 3.12 kernel:
-the usb driver (dwg_otg?) isn't taking up significant CPU.
-Pulseaudio is streaming @ 96khz stereo sample rate over ethernet with ~20% CPU load!
Negative changes:
-The recording level is VERY low. I have to turn the caputre volume all the way up in alsamixer (I belive this is the digtal volume in the usage scripts) in order to get something close to a normal recording level. Something is not quite right here as I only had to make a minor change to the output gain before (32 -> 40).
-Now the showstopper. I'm getting terrible imaging on rf signals. SDR software relies upon differences in phase of the L & R audio channels to determine where to place the signal in the rf spectrum. Something has changed that is affecting channel phase causing duplicated signals. I've double checked that the card is not recording in mono (which it doesn't appear to be based on pulseaudio info). The strange thing is, this card was giving very good image rejection with the older kernel patches compared to a cheap PCM2902 USB card. I've tried adjusting channel phase in the software but the image rejection is not responding adequately. I've also tried delaying both L & R channels by one sample independently, but that didn't help.
I've posted these concerns to the github pull request page, but thought I would check here to see if anyone has tried the new kernel updates. I don't mind being a beta tester for such a quality ADC/DAC card, but I'm a little concerned that we're going to loose support before the bugs are worked out.
Thanks.
