Hi
I am trying to configure TegraX1 SoC and Realtek5677 codec. These two drivers have different meaning of FSYNC polarity in TDM mode A format.
* TegraX1 driver thinks that "normal" polarity is when a frame starts with FSYNC falling edge. TegraX1 applies it to all formats (I2S, PCM/TDM mode A). And inverted FSYNC means that frame starts with rising edge of FSYNC.
* RT5677 thinks that "normal" for I2S is "frame starts with falling edge". And for TMD mode A "normal" means "frame starts with rising FSYNC edge".
Thus normal/inverted FSYNC in TDM mode A are opposite at these 2 chips. Which one is correct? What is exact definition of SND_SOC_DAIFMT_xB_yF constants in soc-dai.h?
I tried to google if I2S spec [1] defines FSYNC polarity but no luck.
It worth to clarify definition of BCLK polarity as well. I believe "normal" BCLK is "line sensing happens at rising edge", "inverted" BCLK - "line sensing happens at falling edge". Is it correct?
[1] https://web.archive.org/web/20060821114007/http://www.semiconductors.philips...