Re: Surface 3 Pen (BLE HID) not sending events

[Johan Hedberg <johan.hedberg@gmail.com>]

Hi Bastien,

On Tue, Oct 17, 2017, Bastien Nocera wrote:
> The Surface 3 pen (part of the 2nd generation of Surface pens[1]) uses
> Bluetooth LE for its top button, which one can assign to a function,
> usually a note taking application on Windows.
> 
> After pairing, bluez throws away all the characteristics, UUIDs and
> other properties it gathered[2].
> 
> Subsequent attempts at pressing the pen button just throws a wobbly[3].
> 
> Any ideas? This apparently used to work, and there's some very hacky
> solutions for those devices:

Do you happen to have a btmon log of the pairing? The reason could e.g.
be that the device doesn't set the bonding flag (in which case our
discarding of information is at least specification-wise correct). The
HCI log you posted seems to be a reconnection when pairing has already
happened. Also, please avoid using hcidump since it does a worse job of
decoding stuff (especially newer protocol features).

Johan