Hi,

after a little trial an error, I found out that the hidraw interface  
simplifies/abstracts a couple of things, and that the USB report  
return data included the report number (02), so all that is needed to  
switch between middle button = scroll and middle button = button2 is

echo -ne "\x02\x03\x00\x00\x00" | sudo tee /dev/hidraw1
and
echo -ne "\x02\x03\x01\x00\x00" | sudo tee /dev/hidraw1

Same would be

echo -ne "\x02\x06\x00\x00\x00" | sudo tee /dev/hidraw1
and
echo -ne "\x02\x06\x01\x00\x00" | sudo tee /dev/hidraw1

to toggle between tap-to-click and not. The device /dev/hidraw1 is from
dmesg | grep Crucialtek | grep hid

Thanks!!!

Stefan

On Fri 12 Aug 2016 09:41:25 PM CEST, Stefan Seidel  
[off-list ref] wrote:

Hi Benjamin,

thanks.

quoted

The answer is different in the first case and 7 seconds after (I assume
you toggled the setting there) -> frame 16 and 33 in the first log.

I'd say the first log would be:
- 1.  -> SET_IDLE (you can ignore it)
- 3.  -> SET_REPORT on OUTPUT 2, length 5 no data
     -> answer in 4.  -> 02 04 02 00 00
- 5.  -> SET CONFIGURATION Status (ignore this as well I think)
- 6.  -> SET_REPORT on OUTPUT 2, length 5 no data
     -> answer in 7.  -> 02 06 00 00 00
- 9.  -> SET_REPORT on OUTPUT 2, length 5 no data
     -> answer in 10. -> 02 05 01 00 00
- 12. -> SET_REPORT on OUTPUT 2, length 5 no data
     -> answer in 13. -> 02 02 01 00 00
- 16. -> SET_REPORT on OUTPUT 2, length 5 no data
     -> answer in 14. -> 02 03 01 00 00

The second sequence (frames 18 to 34) provides the same output except
for the last answer 02 03 00 00 00.

Yes, that was my analysis as well. Thanks for confirming this.

quoted

The "no data" part seems weird, but there is a chance if you output a
report with 02 03 00 00 00 or 02 03 01 00 00, this toggles the behavior.

Yes, I was wondering about exactly that, maybe I need to read up on  
the limitations of USBPcap to find out why apparently no outgoing  
data is reported. But I will try sending it as you suggest.

quoted

If you start working in kernel space, start with a small hid driver and
in .probe() try accessing the device with the event sequences you got.

If you start working with hidraw, there is an example in the kernel
tree: samples/hidraw/hid-example.c.

Thanks for these hints! I realized I already did work on HID stuff  
once when I amended a userspace program for a USB FM transmitter  
that registered as HID device. I will try your suggestions.

Stefan