[Bug 268502] Re: Bluetooth doesn't work (hci_cmd_task: hci0 command tx timeout)

[SrinivasaMoorthy]

I have tested this on Karmic, Lucid and Maverick and continued to find
this problem (timeout). After some googling and debugging, I found this
bug #453885 specifying in detail and also the workaround from that bug.

First, here's the workaround for those (like me) who want to get
bluetooth working in Karmic / Lucid / Maverick: (I have tried this only
on Karmic)

1. Downgrade your bluez package to the jaunty's version. (apt-get remove bluez, dpkg -i <jaunty's 4.32-0ubuntu4 deb file>)
2. You may want to install blueman, since gnome-bluetooth has other package dependencies)

I have got it finally working consistently and without any issues, after
this!!!

My Device details:

Bus 002 Device 015: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth
Dongle (HCI mode)

Based on my debugging and the info from bug #453885, I noticed the
following:

a. After the device initializes, /usr/sbin/bluetoothd is issuing the
command to the device "Read Default Link Policy Settings" and there is
no response from the device. This may happen because the device does not
support and is a HCI Version 1.1 and/or bluez cannot handle such devices
(and ignores the error that encountered by the prev "Write Default Link
Policy Settings").

b. Even though there is no response to this command, there is no syslog
error indicating a timeout.

c. Most usually at this time, the hci0 interface would say "UP RUNNING"
without any "PSCAN". The moment you issue any action (hciconfig hci0
pscan or hcitool scan), the kernel issues a timeout syslog error -- to
the previous "Read Default Link Policy Settings" command.

d. After this, it goes haywire and nothing works. It has worked very few
times though for me (scanning or browsing files) -- I am not entirely
sure how -- but it stops working after sometime, and I suspect it would
have hit the above scenario. However, during the entire period I was
testing with hcidump on, it never worked and I can't say how the
scanning was successful a time or two.

e. bluez 4.32 did not issue the "Read Default Link Policy Settings"
command, so this issue never comes up.

f. To me the issue can be resolved by fixing bluez that should not issue
"Read Default Link Policy Settings" command, for devices that does not
support it (I am not very sure, but this may be due to HCI ver 1.1 on
the device, which you can look at by hciconfig -a) and/or properly
handle errors if the HCI command was not responded.

-- 
Bluetooth doesn't work (hci_cmd_task: hci0 command tx timeout)
https://bugs.launchpad.net/bugs/268502
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