[PATCH 4.12 17/43] HID: wacom: Do not completely map WACOM_HID_WD_TOUCHRINGSTATUS usage

Greg Kroah-Hartman
2017-09-08T13:40:29Z

From: Jason Gerecke <killertofu@gmail.com>

commit 8d411cbf46e515ca2b7ceb3d2b3f43e22813edac upstream.

The WACOM_HID_WD_TOUCHRINGSTATUS usage is a single bit which tells us
whether the touchring is currently in use or not. Because we need to
reset the axis value to 0 when the finger is removed, we call
'wacom_map_usage' to ensure that the required type/code values are
associated with the usage. The 'wacom_map_usage' also sets up the axis
range and resolution, however, which is not desired in this particular
case.

Although xf86-input-wacom doesn't do really do anything with the ring's
range or resolution, the libinput driver (for Wayland environments)
uses these values to provide proper angle indications to userspace.

Fixes: 60a2218698 ("HID: wacom: generic: add support for touchring")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hid/wacom_wac.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -1767,7 +1767,13 @@ static void wacom_wac_pad_usage_mapping(
features->device_type |= WACOM_DEVICETYPE_PAD;
break;
case WACOM_HID_WD_TOUCHRINGSTATUS:
- wacom_map_usage(input, usage, field, EV_ABS, ABS_WHEEL, 0);
+ /*
+ * Only set up type/code association. Completely mapping
+ * this usage may overwrite the axis resolution and range.
+ */
+ usage->type = EV_ABS;
+ usage->code = ABS_WHEEL;
+ set_bit(EV_ABS, input->evbit);
features->device_type |= WACOM_DEVICETYPE_PAD;
break;