I have the MinnowBoard Max with Baytrail Atom (ValleyView) SoC. I'm attempting to write an Alsa (ASoC) driver for my sound card to work with this board. PCM should work through I2S for this sound card I have.
Good to hear. There are several folks in Intel trying to enable I2S over the low-speed connector for 3rd party enablement or help 'makers'. This is still work-in-progress but we can already share some elements of information based on our own experience: 1. the default 0.82 firmware doesn't enable the I2S pins, we are currently using a DSDT override to configure them. 2. the audio codec needs to be registered as a child of I2C6 (it's typically I2C2 on regular baytrail platforms). this is also part of the DSDT override. 3. since we need to support multiple audio codecs, we'd like to add a mechanism to add information in the SSDT table to be able to boot the same kernel and select the right drivers. Alternatively you will have to use the DSDT override method until this mechanism is ready. 4. there is no MCLK on existing MinnowBoards, so your codec will have to drive its PLL from the BLCK. newer versions of the MinnowBoard Turbot will support an MCLK but they are in pre-production stage and to the best of my knowledge not available commercially yet. 5. to get the best long-term support you really want to use the newer DPCM-based driver/firmware for e.g 24-bit, TDM and deep-buffer support. We have a set of patches that have not been published upstream yet but if you are interested you can look at my github https://github.com/plbossart/sound/tree/minnow-v4.3-24bit. In theory if you take this code and change the DSDT to support your _HID just like it was done for the rt5651 the drivers should load and register a sound card. Disclaimer: there is no official support on this branch and rebases/fixes may happen at any time. the code will be submitted upstream when ready.
If you provide more information on which codec you are trying to link to we can help further. -Pierre