Surface Laptop 3: Touchpad & Keyboard support

[archseer]

Depends on linux-surface/linux-surface#17

Fixes #22
Refs jakeday/linux-surface#591

[archseer]

Also fixes caps lock light on SL3, refs #8. Potentially also working for SL1/2 if the same iid/cid is used but we need someone to verify.

[mistay]

Really nice work, Thanks @archseer!

[archseer]

@qzed So I was about to say that this PR is ready, but there seems to be a kernel panic going on. I can trigger it by swiping the touchpad extremely fast, but I've also had it happen when running insmod.

(edit: resolved)

[archseer]

@qzed Likely we want to do the hid_add_device even later, right before returning?

hid-multitouch will start doing things as soon as the HID device is detected

[qzed]

I think this should (mostly) work as is. The core driver is able to send output reports and set/get feature reports without the events on the EC being disabled. It breaks when the driver expects some input report being sent from the EC as response (as that's not enabled at this point). I don't have any idea if that's possible or done in practice, so we might want to change that.

If we want to change that: I think we should first set up the EC events and enable them, and then register the HID device to ensure other drivers can actually use it before we add it. Similarly on removing, first de-register/destroy the HID device and then remove and disable the events. That will require us to check if the HID device is set up in the event handler function, Which should be possible via an atomic bool or something.

[qzed]

Okay, mostly minor things. I'm not sure about the placement of the hid_add_device call and will check that. Good work so far!

[mistay]

@qzed, @archseer thanks for this session!

[qzed]

Thanks!

Also you're alright with me adding

MODULE_AUTHOR("Blaž Hrastnik <blaz@mxxn.io>");
MODULE_DESCRIPTION("Driver for HID devices connected via Surface SAM");
MODULE_LICENSE("GPL v2");

(for integration into the kernel)?

Edit: Approved via IRC.