Pi DAC+ fails on Pi 5

[Dave Jones]

[Impact]

First reported on the Raspberry Pi forums (https://forums.raspberrypi.com/viewtopic.php?p=2162847), I've since confirmed that the Raspberry Pi DAC+ HAT (formerly the IQaudIO DAC+ HAT, which is basically the same board) works happily under RaspiOS on the Pi 5, but not Ubuntu 23.10 or 24.04.

The board *does* work on Ubuntu on prior models, including 3B+ and 4B (those are all I've tested so far), but it does require the overlay (iqaudio-dacplus or rpi-dacplus depending on the variant) to be manually specified in config.txt (RaspiOS automatically detects and loads the board; I haven't figured out why we don't yet but that's an additional data-point that may be worth exploring).

Anyway, on the Pi 5 the HAT is detected (/proc/device-tree/hat/uuid is populated with the correct value, and /proc/device-tree/hat/product lists "Pi-DAC+" which is correct), but the following appears in dmesg:

[ 7.383734] designware-i2s 1f000a0000.i2s: Missing dma channel for stream: 0
[ 7.392977] designware-i2s 1f000a0000.i2s: ASoC: error at snd_soc_pcm_component_new on 1f000a0000.i2s: -22
[ 7.403212] snd-rpi-iqaudio-dac soc:sound: ASoC: can't create pcm Raspberry Pi DAC+ HiFi :-22
[ 7.405612] rpivid 1000800000.codec: bcm2712_iommu_of_xlate: MMU 1000005100.iommu
[ 7.416183] rpivid 1000800000.codec: bcm2712_iommu_probe_device: MMU 1000005100.iommu
[ 7.418036] snd-rpi-iqaudio-dac soc:sound: snd_soc_register_card() failed: -22

[Test Case]

See impact above.

[Fix]

Build AXI dma driver into the kernel rather than a loadable module.

[Where Problems Could Occur]

At boot and when SPI-devices are attached.

[Dave Jones (waveform)]

Incidentally, this is the product in question:

https://www.raspberrypi.com/products/dac-plus/

I've been using one of the older IQaudIO DAC+ boards, but I'm told they're electrically equivalent; they were just rebranded when Raspberry Pi started producing them directly.

[Juerg Haefliger (juergh)]

I can confirm that I'm seeing the same issue with a hifiberry miniamp on Pi 5 running Noble.