On Wed, 6 Nov 2019, Gerecke, Jason wrote: > From: Jason Gerecke <killertofu@xxxxxxxxx> > > The HID descriptors for most Wacom devices oddly declare the serial > number and other related fields as signed integers. When these numbers > are ingested by the HID subsystem, they are automatically sign-extended > into 32-bit integers. We treat the fields as unsigned elsewhere in the > kernel and userspace, however, so this sign-extension causes problems. > In particular, the sign-extended tool ID sent to userspace as ABS_MISC > does not properly match unsigned IDs used by xf86-input-wacom and libwacom. > > We introduce a function 'wacom_s32tou' that can undo the automatic sign > extension performed by 'hid_snto32'. We call this function when processing > the serial number and related fields to ensure that we are dealing with > and reporting the unsigned form. We opt to use this method rather than > adding a descriptor fixup in 'wacom_hid_usage_quirk' since it should be > more robust in the face of future devices. > > Ref: https://github.com/linuxwacom/input-wacom/issues/134 > Fixes: f85c9dc678 ("HID: wacom: generic: Support tool ID and additional tool types") > CC: <stable@xxxxxxxxxxxxxxx> # v4.10+ > Signed-off-by: Jason Gerecke <jason.gerecke@xxxxxxxxx> > Reviewed-by: Aaron Armstrong Skomra <aaron.skomra@xxxxxxxxx> Applied to for-5.4/upstream-fixes. -- Jiri Kosina SUSE Labs
