On more recent kernels legacy HDA stops working for device 8086:9d71: [ 47.211381] snd_hda_intel 0000:00:1f.3: DSP detected with PCI class/subclass/prog-if info 0x040100 [ 47.211383] snd_hda_intel 0000:00:1f.3: Digital mics found on Skylake+ platform, using SST driver
However, only legacy HDA supports it: 00:1f.3 Multimedia audio controller [0401]: Intel Corporation Sunrise Point-LP HD Audio [8086:9d71] (rev 21) .. Kernel modules: snd_hda_intel
Ubuntu kernel doesn't select SND_SOC_INTEL_SKYLAKE, which builds snd-soc-skl, because based on the Kconfig description SOF should support it.
I wonder if SND_SOC_INTEL_SKYLAKE should be select again?
SOF does not support Skylake and Kabylake, and only the Up2 board for APL. I am not sure what you mean by 'recent' kernels since this dynamic selection has been in place for a year now?
At any rate, to make this work again:
1. You can select SND_SOC_INTEL_SKYLAKE or alternatively to be more accurate:
SND_SOC_INTEL_SKL SND_SOC_INTEL_APL SND_SOC_INTEL_KBL
There are known issues with Conexant codecs, typically on HP devices, only Realtek codecs are supported.
2. In addition you will need to have the topology for SKL/KBL w/ HDaudio codecs. It's in alsa-topology-conf but would need to be compiled and installed.
3. UCM files should be already handled in alsa-ucm-conf
Hope this helps -Pierre