Hi, everyone !
I'm bringing up a wm8731 audio codec on an iMX6 based board. I use the slave mode, i.e. SSI outputs all the clocks towards the codec IC. I work with 3.0.35 Android kernel provided by freescale.
While, generally, the playback is Ok, I face 2 issues: - cannot play back mono streams (too high rate, one speaker produces only noise) - cannot play back streams with sampling rate as low as 8kHz (the sound is accompanied by high distortion) In the mainline kernel (commits to v3.6), there is a workaround to the 1-st issue by simply removing mono support from imx-ssi.c. Similar approach would fix the 2-nd issue as well - SSI would report it does not support 8kHz sampling rate. In a later commit, this workaround has been reverted, enabling mono support back.
My question is this: Is this a real limitation of SSI ? Does it support mono playback or not ? Does SSI support 8kHz sampling rate ? If yes, what could be possible reason to the distortions I get, while higher rates are played back well ? Is there a real fix to these issues, or only workarounds are available ?
Thanks, Andrey Gelman