Re: [Bluez-devel] Increasing HIDP_DEFAULT_MTU ?

[Marcel Holtmann <marcel@holtmann.org>]

Hi Pascal,

> I have a Bluetooth HID peripheral which sends 50-byte payloads
> on L2CAP psm 19, even though it has accepted a Config req with
> MTU 48.  As a result, the data never reaches userspace.
> Is this a bug in the device ?

which device is this. I might need to have one of it at home for
testing.

> Besides, even if the device implemented segmentation with
> DATC, a MTU of 48 might be a significant performance penalty
> (generating twice as many packets on the radio channel ?).

Actually we are not really supporting segmentation by ourself. If I had
one of the devices for testing, I might be able to fix that easily. Hint
hint :)

> So would it be appropriate to change
> bluez-libs-3.11/include/hidp.h:#define HIDP_DEFAULT_MTU 48
> to 672, as recommmended by HID_SPEC_V10 section 7.5.2 ?
> 
> Or maybe make it a command-line option for hidd and
> bluetoothd-service-input ?

I fixed the input service now. We will see how this works out. In
addition the 2.6.22-rc3 kernel contains a patch to fix a bug in the
L2CAP config handling.

Regards

Marcel



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