Created attachment 224291 [details] patch that adds type cover 4 support. This only happens to me after a specific firmware update from Microsoft. (7/14 updates). https://www.microsoft.com/surface/en-us/support/install-update-activate/surface-pro-4-update-history When I boot the surface with type cover 4 plugged in and boot into linux, the type cover will work properly (kernel is with a patch applied to add device id, patch can be found in attachment). But if I either suspend and resume the Surface, or unplug the type cover and replug it again, the type cover 4 will stop working. Type cover can still be recognized by kernel (checked by lsusb/dmesg). But it doesn't work and the led light on type cover also not light up and doesn't work under either tty or X11.
ping :)
Weng, please send your patch directly to Jiri Kosina <jkosina@suse.cz> (who is maintainer of HID drivers) and CC Benjamin Tissoires <benjamin.tissoires@redhat.com> and linux-input@vger.kernel.org mailing list. You can also discuss there the issues you are seeing with the cover after suspend/resume. Thanks!