Re: [gentoo-user] Bluetooth disappeared because of MSWindows?

[Mick]

On Sunday 06 Dec 2015 07:22:37 Alan McKinnon wrote:
> On 06/12/2015 01:31, Mick wrote:
> > 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.
>
> We've had a few cases of things like this on the list over the years. It
> always end up probably a Linux driver bug. Here's what seems to happen:
>
> The hardware needs to be enabled/shutdown/fiddled or whatever in some
> magic way that windows knows about but linux doesn't. Booting into
> Windows applies the magic so when you reboot into Linux it's now in a
> state Linux can use.

Yes, this makes sense.  The hickups with the audio would always happen when I 
booted on battery, so I thought at the time that they were related to Linux's 
power management.


> Read the kernel docs for your driver, the odds are good you have to
> apply a driver tweak for your hardware to make it work right.

I have had a look at the Doc but haven't been able to find anything.  This is 
my device:

Bus 002 Device 008: ID 413c:8156 Dell Computer Corp. Wireless 370 Bluetooth 
Mini-card
Bus 002 Device 005: ID 0a5c:4500 Broadcom Corp. BCM2046B1 USB 2.0 Hub (part of 
BCM2046 Bluetooth)


> Then do a Google search for your hardware and laptop types, see what the
> interwebz have to say.

I came across this bug report, although not directly relevant to my symptoms:

https://bugzilla.kernel.org/show_bug.cgi?id=47231

There are loads of Ubuntu users reporting that their bluetooth is nowhere to 
be seen, but I didn't find any solutions there.
-- 
Regards,
Mick