* [PATCH] HID: wacom: Avoid entering wacom_wac_pen_report for pad / battery
@ 2020-09-23 20:14 Gerecke, Jason
2020-09-25 11:15 ` Jiri Kosina
0 siblings, 1 reply; 2+ messages in thread
From: Gerecke, Jason @ 2020-09-23 20:14 UTC (permalink / raw)
To: linux-input, Jiri Kosina, Benjamin Tissoires
Cc: Ping Cheng, Aaron Armstrong Skomra, Jason Gerecke, stable, Ping Cheng
From: Jason Gerecke <jason.gerecke@wacom.com>
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>
---
drivers/hid/wacom_wac.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
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);
--
2.28.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] HID: wacom: Avoid entering wacom_wac_pen_report for pad / battery
2020-09-23 20:14 [PATCH] HID: wacom: Avoid entering wacom_wac_pen_report for pad / battery Gerecke, Jason
@ 2020-09-25 11:15 ` Jiri Kosina
0 siblings, 0 replies; 2+ messages in thread
From: Jiri Kosina @ 2020-09-25 11:15 UTC (permalink / raw)
To: Gerecke, Jason
Cc: linux-input, Benjamin Tissoires, Ping Cheng,
Aaron Armstrong Skomra, Jason Gerecke, stable, Ping Cheng
On Wed, 23 Sep 2020, Gerecke, Jason wrote:
> From: Jason Gerecke <jason.gerecke@wacom.com>
>
> 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>
Applied.
--
Jiri Kosina
SUSE Labs
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