Hi there, A while back I put out this thread: How do I set up multiple codecs on one I2S - without TDM?" https://lore.kernel.org/all/ZMBRMnv0GQF4wyfQ@titan/ This is my specific use case and motivation for this patch series. I posted how I managed to configure the audio-graph-card2 to allow doing this in conjunction with some register hacking, but I now have an initial patch series to support this in the sun4i-i2s driver. Now I've tested this on the T113-s3 with 3 wm8782s and it works well, but I'm marking this as RFC as I think I'm out of my depth here and I'd like to know the direction I need to take this: I'm new to kernel development and I'm genuinely unsure what are best practices and which are bad practices design-wise. My main concerns are the following: First, I split up channel-dins and channel-slots. This is mainly because I implemented one first but both of them only make sense together. The registers themselves use a format of a byte per channel with the upper nibble being the din and the lower being the slot. Perhaps this is a better format to copy? Second, I use u8 arrays on the device tree. This is done so I can just read the array easily, but it also means I can't make this property contingent on a compatible string in the schema as $ref doesn't seem to be allowed there. Third, channel-slots is available on all sun4i-i2s controllers, but I only have it implemented on the R329 variant for now when there are multiple din pins. I could add support for this on older controllers but there's not really a use case for manual configuration as there's no DIN and I don't have hardware to test it on. Fourth, I don't limit the readable channels to the channels listed. Reading more channels than you have currently results in the controller assuming you want to use TDM, but that's not the case here and you can have strange duplicate channels show up. Fifth, it might be a good idea to increase the maximum channels from 8 to 16, especially if people are going to be running multiple TDM streams on one controller. Sixth, the channel-slots only apply to capture, not playback. This is something I just realized now when writing and forgot to document in the patch set. Thanks for your time, John. John Watts (7): ASoC: sunxi: sun4i-i2s: Prepare for runtime DIN pin selection ASoC: sunxi: sun4i-i2s: Use channel-dins device tree property ASoC: sunxi: sun4i-i2s: Prepare for runtime channel slot selection ASoC: sunxi: sun4i-i2s: Use channel-slots device tree property ASoC: sunxi: sun4i-i2s: Detect TDM slots based on channel slots dt-bindings: sound: sun4i-i2s: Add channel-dins property dt-bindings: sound: sun4i-i2s: Add channel-slots property .../sound/allwinner,sun4i-a10-i2s.yaml | 30 +++++ sound/soc/sunxi/sun4i-i2s.c | 106 +++++++++++++++++- 2 files changed, 132 insertions(+), 4 deletions(-) -- 2.41.0
