
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
1.7 KiB
Chrome OS EC Support
Introduction
This plugin provides support for the firmware updates for Chrome OS EC project based devices.
Initially, it supports the USB endpoint updater, but lays the groundwork for future updaters which use other update methods other than the USB endpoint.
This is based on the chromeos ec project's usb_updater2 application [1].
Information about the USB update protocol is available at [2].
Firmware Format
The daemon will decompress the cabinet archive and extract a firmware blob in the Google fmap [3] file format.
This plugin supports the following protocol ID:
- com.google.usb.crosec
GUID Generation
These devices use the standard USB DeviceInstanceId values, e.g.
USB\VID_18D1&PID_501A
Update Behavior
The device usually presents in runtime mode, but on detach re-enumerates with the same USB PID in an unlocked mode. On attach the device again re-enumerates back to the runtime locked mode.
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.
Vendor ID Security
The vendor ID is set from the USB vendor, which is set to various different values depending on the model and device mode. The list of USB VIDs used is:
USB:0x18D1
External interface access
This plugin requires read/write access to /dev/bus/usb
.
[1] https://chromium.googlesource.com/chromiumos/platform/ec/+/master/extra/usb_updater/usb_updater2.c [2] https://chromium.googlesource.com/chromiumos/platform/ec/+/master/docs/usb_updater.md [3] https://www.chromium.org/chromium-os/firmware-porting-guide/fmap