- Compiled and installed Linux kernel 4.10 rc8
-> Microphone mute led does not work
This is even more confusing. Between 4.9, which you claim works fine, and 4.10-rc8, which you claim does not work, I can see no changes to either drivers/leds/dell-led.c or sound/pci/hda/dell_wmi_helper.c. Kernel configuration issue?
I was surprised too, and I compiled it twice and installed on both Ubuntu 16.04 and 16.10.
I would guess it is config too. On 4.9, it was using Ubuntu default. On 4.10rc8, I am pretty much using the instruction on https://wiki.ubuntu.com/KernelTeam/GitKernelBuild. The .config is available @ http://paste.ubuntu.com/24001113/
In Patch 6/6 is: Kconfig option is renamed from CONFIG_LEDS_DELL_NETBOOKS to CONFIG_DELL_WMI_LED. So you need to update your config for testing.
I also thought about this, but CONFIG_DELL_WMI_LED is only needed to support the Dell Activity LED (present in the Dell Latitude 2100 netbook). Meanwhile, Alex is only testing the microphone mute LED, which requires CONFIG_DELL_LAPTOP to be enabled. The cover letter for this patch series provides a more thorough explanation.