[Gta04-owner] Bluetooth speed (II)

Christoph Mair christoph.mair at gmail.com
Tue Oct 25 21:29:07 CEST 2011


as Nikolaus noted earlier the bluetooth speed is somewhat limited.
This is because of the slow (115200 Bits/s) interface between the
bluetooth chip and the OMAP. But the datasheets clearly specify that
both components should support higher speeds too.
With kernels older than 2.6.34 you can't use higher speeds than 115200
because of missing driver support. But there is still hope: the brand
new 3.x kernel comes with a new UART driver which supports much higher
baudrates. The only thing left is the bluetooth chip itself: it will
use the preconfigured (slow) baudrate every time you power it up. The
good news is: this behavior can be changed!

Here is how to boost the speed to 3MBaud:

(From http://projects.goldelico.com/p/gta04-kernel/page/Wireless/#wikititle_9)

This assumes kernel 3.x as the UART speed of older kernels might be
limited to 115200. Also note the slightly different name of the tty.

hciattach -s 115200 /dev/ttyO0 any 115200 flow
hciconfig hci0 up
bccmd -d hci0 psset baudrate 12288
bccmd -d hci0 warmreset
killall hciattach
hciattach -s 3000000 /dev/ttyO0 any 3000000 flow
hciconfig hci0 up

If everything went right (watch your kernel log for tx timeout error
messages) you should now get the full bluetooth 2.0 EDR speed.

This change is not permanent and has to be done every time you power
up the Wi2Wi module.

If you want to permanently save it (be sure to try it out first and
only save a working value; you could brick the bluetooth chip) read
the documentation:

Have fun!


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