Re: [Bluez-devel] LED Output Reports to Keyboard

[Marcel Holtmann <marcel@holtmann.org>]

Hi Jon,

> Right place to talk about the Bluez source code that is now in the Linux 
> Kernel? Hope so.
> 
> In essence: testing with kernel 2.6.22, it seems to me that LED 
> information is sent to bluetooth devices using the boot protocol 
> regardless of whether the boot protocol is active and even if the device 
> explicitly declares that it doesn't support boot protocol.
> 
> 
> 
> In detail:  I'm designing a Bluetooth keyboard device which has some 
> LEDs which are for customised use.   This means that they have ID 
> numbers that cannot be represented in the boot protocol keyboard output 
> report.  So, the device has a customised report descriptor. The first 
> byte of the output report is the same as the boot protocol but a second 
> byte is added containing eight more LED flags. 
> 
> I'm testing my device on a laptop running Fedora Core 6 with kernel 
> 2.6.22.  Digging in the kernel source code I found that the LED output 
> reports are sent from the function hidp_queue_event in the source file 
> net/bluetooth/hidp/core.c.  I added an extra line for debugging;
> 
>     BT_DBG("Sending keyboard boot protocol LED output report. Session is 
> in %s mode.",
>         ((session->flags & (1 << 
> HIDP_BOOT_PROTOCOL_MODE))?"boot":"report") );
> 
> which confirms that the HIDP module has correctly understood from my 
> service record that boot protocol mode is not set.  The rest of this 
> function however sends a hard wired boot protocol frame and therefore 
> ignores completely any LED events that cannot be represented.  In fact 
> for my customised LEDs no frame is sent at all since to this function it 
> seems that no significant LED has changed state.
> 
> By the way, I also use a customised input report for key presses which 
> is handled perfectly O.K.
> 
> First question: can anyone tell me that the more unusual LED events do 
> get through to their Bluetooth keyboard when using Linux?  It is of 
> course possible that I've messed up my Service Record and all of the 
> above is a load of tosh.
> 
> Second question: actually I'll not dive into a load more questions about 
> fixing the bug until I know that I've actually found one.

don't force it to use the boot protocol mode. Lets use Linux the report
protocol mode and make sure your HID report descriptor is sane. Then we
can fix it up in the common HID parser of Linux to handle you leds.

Run "hcidump -X -V" to show what is send by your keyboard.

Regards

Marcel



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