Dear Audio user,

be informed, that the I2S on the AR9331 is limited to 48kSamples (http://www.scribd.com/doc/132231193/AR9331-datasheet, Page 21):
"SPDIF out audio interface that support up to 48 KHz sampling clock and a serial clock of more than 512 * sampling frequency. It also supports seamless switching of the audio outstream from I to SPDIF."

Iwan

Hi Pepe!

Thanks for your answer! OK I've added your pll config suggestion. Now the code is a little cleaner

Now I've published it on github:
https://github.com/franzflasch/ar9331-i2s-alsa

It is a self contained openwrt package. If you want to use it you have to insert the modules in the following order:
insmod dev-audio.ko
insmod ath79-i2s.ko
insmod ath79-pcm-mbox.ko
insmod wm8727.ko
insmod ath-carambola2.ko

I've included all audio related #defines and iomem variables into these kernel driver files so no openwrt patches are needed. Tested with a more or less up-to-date openwrt trunk version. (Kernel ver 3.14)

There is still some work left - the gpio initialization is very ugly and should be refactored, but all in all I think it is quite useful.

Regards,
Franz

Hi Pepe!

Thanks! You are right these misleading defines were also confusing to me, however I've checked the ar9331 datasheet and found out that the defines which are used on the pcm and mbox part are absolutely compatible to the ar9331. It seems the only difference to the ar9344 is the GPIO initialization and the PLL (ar9331 does not have a DPLL)

Yes, the target would be official support in openwrt, however to reach this goal there is quite some refactoring needed.

By the way: I found, that deveveloping on this alsa stuff is a real pain. How can somenone test the mbox or i2s in the developing phase? Is there any alsa test interface? Development on a new driver from scratch must be absolutely horrorful...

Anyways, thanks!

Regards,
Franz