path: root/drivers/hid/wacom_wac.c
diff options
authorJason Gerecke <jason.gerecke@wacom.com>2020-09-23 13:14:56 -0700
committerJiri Kosina <jkosina@suse.cz>2020-09-25 13:14:16 +0200
commitd9216d753b2b1406b801243b12aaf00a5ce5b861 (patch)
tree13386f866f8d72ea30eb8d7860c75dcf82c6cb5e /drivers/hid/wacom_wac.c
parentca43ab1e54c0898a6e1b40d99ffd7f57c5c42257 (diff)
HID: wacom: Avoid entering wacom_wac_pen_report for pad / battery
It has recently been reported that the "heartbeat" report from devices like the 2nd-gen Intuos Pro (PTH-460, PTH-660, PTH-860) or the 2nd-gen Bluetooth-enabled Intuos tablets (CTL-4100WL, CTL-6100WL) can cause the driver to send a spurious BTN_TOUCH=0 once per second in the middle of drawing. This can result in broken lines while drawing on Chrome OS. The source of the issue has been traced back to a change which modified the driver to only call `wacom_wac_pad_report()` once per report instead of once per collection. As part of this change, pad-handling code was removed from `wacom_wac_collection()` under the assumption that the `WACOM_PEN_FIELD` and `WACOM_TOUCH_FIELD` checks would not be satisfied when a pad or battery collection was being processed. To be clear, the macros `WACOM_PAD_FIELD` and `WACOM_PEN_FIELD` do not currently check exclusive conditions. In fact, most "pad" fields will also appear to be "pen" fields simply due to their presence inside of a Digitizer application collection. Because of this, the removal of the check from `wacom_wac_collection()` just causes pad / battery collections to instead trigger a call to `wacom_wac_pen_report()` instead. The pen report function in turn resets the tip switch state just prior to exiting, resulting in the observed BTN_TOUCH=0 symptom. To correct this, we restore a version of the `WACOM_PAD_FIELD` check in `wacom_wac_collection()` and return early. This effectively prevents pad / battery collections from being reported until the very end of the report as originally intended. Fixes: d4b8efeb46d9 ("HID: wacom: generic: Correct pad syncing") Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com> Reviewed-by: Ping Cheng <ping.cheng@wacom.com> Tested-by: Ping Cheng <ping.cheng@wacom.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid/wacom_wac.c')
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 1c96809b51c9..b74acbd5997b 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2773,7 +2773,9 @@ static int wacom_wac_collection(struct hid_device *hdev, struct hid_report *repo
if (report->type != HID_INPUT_REPORT)
return -1;
- if (WACOM_PEN_FIELD(field) && wacom->wacom_wac.pen_input)
+ if (WACOM_PAD_FIELD(field))
+ return 0;
+ else if (WACOM_PEN_FIELD(field) && wacom->wacom_wac.pen_input)
wacom_wac_pen_report(hdev, report);
else if (WACOM_FINGER_FIELD(field) && wacom->wacom_wac.touch_input)
wacom_wac_finger_report(hdev, report);