Dell machines have lately started shipping with dual mode hardware. Most notably the i2s and hda modes. The trick is to boot with the right acpi revs and often it requires a cold boot to change mode.
I came across a rather peculiar phenomenon today with my laptop. I realised
that my bluetooth controller was nowhere to be found. I thought running
hciconfig would bring it up, but all it did was to complain that there was no
device found. rfkill would not list it either.
Modprobing various modules did not produce a device, so searching for answers
I thought of booting into MSWindows. After I enabled the device in MSWindows
I rebooted into Linux and was surprised to see the bluetooth controller was
visible again in lspci.
How come that switching off the device in one OS, affects the other? :-/
What should I do next time to enable bluetooth from within Linux?
PS. There's a parallel to this with the same laptop. Some years ago audio
would randomly never come up at boot and no amount of alsactl could wake it
up. A swift reboot into MSWindows would reset audio and all would work fine
in Linux thereafter. Some cursory troubleshooting at the time didn't help me
much. I don't expect that the two issues are related, but thought of
mentioning it just in case.
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Regards,
Mick