078beafb2d
It is far too easy to forget to set FWUPD_DEVICE_FLAG_NO_GUID_MATCHING for new
plugins, and without it it all works really well *until* a user has two devices
of the same type installed at the same time and then one 'disappears' for hard
to explain reasons. Typically we only need it for replug anyway!
Explicitly opt-in to this rarely-required behaviour, with the default to just
use the physical and logical IDs. Also document the update behavior for each
plugin to explain why the flag is being used.
This allows you to have two identical Unifying plugged in without one of them
being hidden from the user, at the same time allowing a HIDRAW<->USB transition
when going to and from bootloader and runtime modes.
This removes the workaround added in 99eb3f06b6.
Fixes https://github.com/fwupd/fwupd/issues/2915
2.4 KiB
Logitech HID Support
Introduction
This plugin can flash the firmware on Logitech Unifying dongles, both the Nordic (U0007) device and the Texas Instruments (U0008) version.
This plugin will not work with the different "Nano" dongle (U0010) as it does not use the Unifying protocol.
Some bootloader protocol information was taken from the Mousejack[1] project, specifically logitech-usb-restore.py and unifying.py. Other documentation was supplied by Logitech.
Additional constants were taken from the Solaar[2] project.
Firmware Format
The daemon will decompress the cabinet archive and extract a firmware blob in a vendor-specific format that appears to be a subset of the Intel HEX format.
This plugin supports the following protocol IDs:
- com.logitech.unifying
- com.logitech.unifyingsigned
GUID Generation
These devices use the standard USB DeviceInstanceId values when in DFU mode:
USB\VID_046D&PID_AAAA&REV_0001USB\VID_046D&PID_AAAAUSB\VID_046D
When in runtime mode, the HID raw DeviceInstanceId values are used:
HIDRAW\VEN_046D&DEV_C52BHIDRAW\VEN_046D
Vendor ID Security
The vendor ID is set from the vendor ID, in this instance set to USB:0x046D
in bootloader and HIDRAW:0x046D in runtime mode.
Update Behavior
The peripheral firmware is deployed when the device is in normal runtime mode, and the device will reset when the new firmware has been written.
The reciever device presents in runtime mode, but on detach re-enumerates with a different USB PID in a bootloader mode. On attach the device again re-enumerates back to the runtime mode. All unifying devices attached to the reciever will not work for the duration of the update.
For this reason the REPLUG_MATCH_GUID internal device flag is used so that
the bootloader and runtime modes are treated as the same device.
Design Notes
When a dongle is detected in bootloader mode we detach the hidraw driver from the kernel and use raw control transfers. This ensures that we don't accidentally corrupt the uploading firmware. For application firmware we use hidraw which means the hardware keeps working while probing, and also allows us to detect paired devices.
[1] https://www.mousejack.com/ [2] https://pwr-Solaar.github.io/Solaar/
External interface access
This plugin requires read/write access to /dev/bus/usb.