PineBook Pro revision 2.2: Wishlist for the hardware issue fixes

[dsimic]

I would also add some weird crackling/popping noises coming out of the speakers while no music playback is active.  I've been unable to correlate those sounds to anything else happening on the laptop, except for the moment of powering off the laptop, which always produces a crackle/pop.

Yes, I had this too.

It could be related to the reported crosstalk between the audio output and the serial console, but the linked description of the crosstalk issue reports garbage on the serial console only with maximum audio playback volume, while I hear weird crackling/popping noises with no audio playback at all.

For the sake of completeness, here's a quotation from the above-linked web page:

Selectable by a hardware switch, the audio jack can be either used for audio or serial console.  A Manjaro developer pointed out a third hardware bug namely crosstalk between the audio and serial line, e.g. when cranking up audio to distortion characters are sent to the console:

# systemctl stop serial-getty@ttyS2
# hexdump -C /dev/ttyS2
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 ff 00  |................|
00000010  00 00 00 00 00 00 00 00  80 00 00 00 00 00 01 00  |................|
00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 f0 00 00  |................|
00000040  00 00 00 00 00 00 00 00  51 00 00 00 00 00 ff 00  |........Q.......|
00000050  00 00 ff 00 fe 00 00 00  e0 00 00 00 00 00 00 00  |................|
00000060  00 00 01 00 00 00 00 80  00 00 00 00 00 00 00 00  |................|
00000070  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

When not disabled in the kernel, these characters are interpreted by the kernel as MAGIC SYSRQs and bring down the kernel every now and then.

Edit: Nope, these two issues are not correlated.  After spending some more time on debugging and researching, I'm positive that I've located the actual source of the crackling/popping noises.   More details will be available in my next post.