Re: [Bluez-devel] "unable to install hw params" to bluetooth (SCO) headset

Stuart Pook
2008-09-23T13:37:05Z

On 23/09/08 15:00, martin f krafft wrote:
> I can reproduce the exact same error with a BT250 hooked up via
> a different bluetooth adapter to an amd64 machine this time (the
> last one was i386), running 2.6.26.

I as said on http://bugzilla.kernel.org/show_bug.cgi?id=11514 aplay and
my JX10 headset work with bluez-4.4 and linux 2.6.26. I only get the
"unable to install hw params" error on 2.6.27-rc5.

> Stuart Pook told me about bluez-utils 4.4 [0] - I am still using 3.36
> [1], but the wiki page says that I need 3.16 or newer. Would
> I have better luck with 4.4? Where does this stuff come in anyway?

I would suggest using bluez-4.x and checking that your headset works
with a 2.6.26 kernel. Note don't use SCO headsets and linux 2.6.26 for
too long as using SCO and the old hci_usb driver will cause your machine
to hard crash sooner or later. The new btusb driver gained SCO support
in 2.6.27-rc4.

> I am running hcid in the background, but I know too little about
> ALSA or Bluetooth to be able to see how the two interlink. The wiki
> mentions a btaudiod, which 3.36 seems not to have. Is that needed?

I don't remember btaudiob. Bluetoothd has replaced hcid. If you run
"bluetoothd -d -n" you will see that aplay (via the bluetooth alsa
libraries) contacts bluetoothd and that it is bluetoothd that connects
to the headset (at least that is how I understand things).

Be careful when you install bluez-4.x that you replace the alsa
bluetooth libraries that aplay uses. I can tell you more about this if
required.

I have added hcidump -XV dumps of the communication between my machine
and my JX10 headset using 2.6.27-rc5 to the bug report mentioned above.
Tomorrow I'll add hcidump -XV using 2.6.26 so that we can see the
differences.

Stuart