I haven't paid as close attention to Xorg issues sine the stroke last year, and I hadn't needed to reboot the box in the living room in several months.
When I did need to, I found that hdmi audio was unlistenable. It sounded like it was mixed witht white noise.
If I boot vmlinuz-3.19.0 is works fine. I had compiled 4.1.0 and 4.5.0, as well as its current default kernel, 4.9.0 (all from Linus' git). All of those 4. kernels show the crappy audio.
In 4.9 I then tried switching to amdgpu. That did not help.
The box has a Kaveri apu (ChipID 0x1313).
Firmware is from linux-firmware.git and is compiled into the kernel via CONFIG_EXTRA_FIRMWARE.
With radeon the kernel command line has: radeon.modeset=1 radeon.audio=1 With amdgpu I switched to: amdgpu.audio=1 amdgpu.exp_hw_support=1
Any thoughs on where to look?
I find it hard to believe that a bug like this could persist for so long.
-JimC