On Tue, 25 Oct 2022 at 09:46, Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> wrote: > Depending on how the device presents itself, we might have to use > hid-logitech-hidpp, not hid-lg FWIW. Ah, indeed it seems to be a hidpp device. I so far wrote code to interact with the device using hidraw and hiddev. What are the implications of a hidpp device? How is hidpp exposed to userspace? >From a search it seems like there are very few userspace programs that handle hidpp on Linux. > And to answer the question "how to map the device to input > "primitives".", it all depends on how the device exports itself. All information that I have gathered so far is on https://github.com/abergmeier/litra_glow_linux. The output of `hidpp-list-features /dev/hidraw0` is: ``` Logi Litra Glow (046d:c900) is a HID++ 4.2 device Feature 0x01: [0x0001] Feature set Feature 0x02: [0x0003] Device FW version Feature 0x03: [0x0005] Device name Feature 0x04: [0x1990] ? Feature 0x05: [0x1eb0] ? (hidden) Feature 0x06: [0x00c2] DFUcontrol 3 (hidden) ``` Is it possible that Feature 0x04 is the protocol for sending changes to the device? All the payload that is sent to the device has a 0x04 directly in front of the instructions. As an example, for turning the light on you send raw bytes: [0x11, 0xff, 0x04, 0x10, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00] 0x10 seems to indicate setting the on state. > > To recap there are 5 hardware buttons and 3 states: > > - State: "Color temperature in range [u, x]" Button: up > > - State: "Color temperature in range [u, x]" Button: down > > - State/Button On/Off > > - State "Brightness in range [y, z]" Button: up > > - State "Brightness in range [y, z]" Button: down > > FWIW, you should be able to use hid-recorder[0] (as root) to record > traces of the events, and to parse them on the fly. Also, if you > provide us the output, we can replay the traces locally as if we > virtually plugged in the device. See the GitHub repo - there are already initial recordings. > FWIW, if the first byte you have to send to control the LED is 0x10, > 0x11 or 0x12 then this is a HID++ device that needs to go in > hid-logitech-hidpp and a lot of groundwork is already done in the > kernel for it. I am trying to get up to speed with hidpp - but I am not there yet. Do you have any hints on what code to read specifically since logitech-hidpp is a bit long... Thanks for the feedback so far
