Hi All,
I have veen working on making the cht_bsw_nau8824 machine driver work together with the sof-audio-acpi driver.
The sof topology files are missing a .tplg file for this setup. Simply copying over the standard sof-byt-codec.tplg file does the trick, but then some mixer setting changes are necessary to fix the right speaker/headphones channel not working. Specifically I need to change the DACR channel setting from CH1 to CH0. But that mixer setting breaks the right channel when used with the sst-acpi driver.
The problem seems to be that the codec and ucm-mixer settings expect DSP_B TDM 4 channel 24 bit format, but the standard sof-byt-codec.tplg file specifies I2S 2 channel 24 bit format.
I tried changing the kernel to program the codec and SSP2 CPU DAIs both at I2S 2 channel 24 bit format to match what most other machine drivers are doing. This causes the no sound on right speaker channel to reproduce with the SST driver too. And like with the SOF driver it can be fixed by changing the mixer setting. With this kernel changes the SOF driver also still needs the mixer-setting fix.
So I can get things to work, and make SOF/SST behave consistent by switching both DAIs to I2S 2 channel 24 bit format and then changing the mixer settings.
The problem is that this will cause regressions unless users update their kernel and UCM in sync...
So I tried to instead change the tplg file so that SOF will use DSP_B TDM 4 channel 24 bit format on the SSP2 DAI side, so that it matches what SST is doing and we don't need to change the mixer settings.
This RFC series reflects my attempts at switching the SSP2 DAI to DSP_B TDM 4 channel 24 bit format when using SOF, unfortunately it does not work, the resulting tplg file causes the following errors:
[ 21.537432] sof-audio-acpi 808622A8:00: Firmware info: version 1:6:0-18fab [ 21.537447] sof-audio-acpi 808622A8:00: Firmware: ABI 3:17:0 Kernel ABI 3:18:0 [ 25.003836] sof-audio-acpi 808622A8:00: Topology: ABI 3:17:0 Kernel ABI 3:18:0 [ 25.216003] sof-audio-acpi 808622A8:00: error: ipc error for 0x80010000 size 12 [ 25.216060] sof-audio-acpi 808622A8:00: error: failed to set DAI config for SSP2-Codec index 2 [ 25.216070] sof-audio-acpi 808622A8:00: error: failed to save DAI config for SSP2 [ 25.216080] sof-audio-acpi 808622A8:00: ASoC: physical link loading failed [ 25.216089] sof-audio-acpi 808622A8:00: ASoC: topology: could not load header: -22 [ 25.217459] sof-audio-acpi 808622A8:00: error: tplg component load failed -22 [ 25.217643] sof-audio-acpi 808622A8:00: error: failed to load DSP topology -22
Which I'm not getting when using the default sof-byt-codec.tplg file.
Possible ways to fix this which I can think of are:
1. Fix SOF and/or the tplg file so that it can do DSP_B TDM 4 channel 24 bit on BYT/CHT.
2. Switch the machine driver over the I2S 2 channel 24 bit, to align it with other machine drivers; and update the UCM files to match. Preferably together with some string in the components string advertised by the kernel so that the UCM files can be written so that they also keep working with older kernels.
3. Keep using DSP_B TDM 4 channel 24 bit with sst-acpi and switch to I2S 2 channel 24 bit with sof-audio-acpi; and update the UCM file to set the mixer settings accordingly depending on which driver is in use.
I'm not sure what the best way to proceed is. To go with solution 1 I'm going to need some help, since I'm stuck there. I find solution 2 tempting because I like the idea of standardising all BYT/CHT machine drivers on using I2S 2 channel 24 bit format between the SSP DAI and the codec DAI. But this means that people upgrading their kernel might see a regression until they update their UCM files too.
Regards,
Hans