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HID: wacom: Read HID_DG_CONTACTMAX directly for non-generic devices

Message ID 20200401212329.23305-1-jason.gerecke@wacom.com (mailing list archive)
State Mainlined
Commit 778fbf4179991e7652e97d7f1ca1f657ef828422
Delegated to: Benjamin Tissoires
Headers show
Series HID: wacom: Read HID_DG_CONTACTMAX directly for non-generic devices | expand

Commit Message

Gerecke, Jason April 1, 2020, 9:23 p.m. UTC
From: Jason Gerecke <jason.gerecke@wacom.com>

We've recently switched from extracting the value of HID_DG_CONTACTMAX
at a fixed offset (which may not be correct for all tablets) to
injecting the report into the driver for the generic codepath to handle.
Unfortunately, this change was made for *all* tablets, even those which
aren't generic. Because `wacom_wac_report` ignores reports from non-
generic devices, the contact count never gets initialized. Ultimately
this results in the touch device itself failing to probe, and thus the
loss of touch input.

This commit adds back the fixed-offset extraction for non-generic devices.

Ref: https://github.com/linuxwacom/input-wacom/issues/155
Fixes: 184eccd40389 ("HID: wacom: generic: read HID_DG_CONTACTMAX from any feature report")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
CC: stable@vger.kernel.org # 5.3+
---
 drivers/hid/wacom_sys.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Benjamin Tissoires April 3, 2020, 11:28 a.m. UTC | #1
On Wed, Apr 1, 2020 at 11:23 PM Gerecke, Jason <killertofu@gmail.com> wrote:
>
> From: Jason Gerecke <jason.gerecke@wacom.com>
>
> We've recently switched from extracting the value of HID_DG_CONTACTMAX
> at a fixed offset (which may not be correct for all tablets) to
> injecting the report into the driver for the generic codepath to handle.
> Unfortunately, this change was made for *all* tablets, even those which
> aren't generic. Because `wacom_wac_report` ignores reports from non-
> generic devices, the contact count never gets initialized. Ultimately
> this results in the touch device itself failing to probe, and thus the
> loss of touch input.
>
> This commit adds back the fixed-offset extraction for non-generic devices.
>
> Ref: https://github.com/linuxwacom/input-wacom/issues/155

I think the official tag is "Link", not "Ref". I changed it.

> Fixes: 184eccd40389 ("HID: wacom: generic: read HID_DG_CONTACTMAX from any feature report")
> Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
> Reviewed-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
> CC: stable@vger.kernel.org # 5.3+
> ---

I really wish we had regression tests for Wacom devices too. This
could have been avoided in the first place.

Anyway, applied to for-5.7/upstream-fixes

Thanks!

Cheers,
Benjamin

>  drivers/hid/wacom_sys.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
> index 5ded94b7bf68..cd71e7133944 100644
> --- a/drivers/hid/wacom_sys.c
> +++ b/drivers/hid/wacom_sys.c
> @@ -319,9 +319,11 @@ static void wacom_feature_mapping(struct hid_device *hdev,
>                         data[0] = field->report->id;
>                         ret = wacom_get_report(hdev, HID_FEATURE_REPORT,
>                                                data, n, WAC_CMD_RETRIES);
> -                       if (ret == n) {
> +                       if (ret == n && features->type == HID_GENERIC) {
>                                 ret = hid_report_raw_event(hdev,
>                                         HID_FEATURE_REPORT, data, n, 0);
> +                       } else if (ret == 2 && features->type != HID_GENERIC) {
> +                               features->touch_max = data[1];
>                         } else {
>                                 features->touch_max = 16;
>                                 hid_warn(hdev, "wacom_feature_mapping: "
> --
> 2.26.0
>
diff mbox series

Patch

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index 5ded94b7bf68..cd71e7133944 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -319,9 +319,11 @@  static void wacom_feature_mapping(struct hid_device *hdev,
 			data[0] = field->report->id;
 			ret = wacom_get_report(hdev, HID_FEATURE_REPORT,
 					       data, n, WAC_CMD_RETRIES);
-			if (ret == n) {
+			if (ret == n && features->type == HID_GENERIC) {
 				ret = hid_report_raw_event(hdev,
 					HID_FEATURE_REPORT, data, n, 0);
+			} else if (ret == 2 && features->type != HID_GENERIC) {
+				features->touch_max = data[1];
 			} else {
 				features->touch_max = 16;
 				hid_warn(hdev, "wacom_feature_mapping: "