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[1/2] HID: wacom: generic: Avoid reporting a serial of '0' to userspace

Message ID 20240201044055.23367-1-tatsunosuke.wacom@gmail.com (mailing list archive)
State Mainlined
Commit ab41a31dd5e2681803642b6d08590b61867840ec
Delegated to: Jiri Kosina
Headers show
Series [1/2] HID: wacom: generic: Avoid reporting a serial of '0' to userspace | expand

Commit Message

Tatsunosuke Tobita Feb. 1, 2024, 4:40 a.m. UTC 
From: Tatsunosuke Tobita <tatsunosuke.tobita@wacom.com>

The xf86-input-wacom driver does not treat '0' as a valid serial
number and will drop any input report which contains an
MSC_SERIAL = 0 event. The kernel driver already takes care to
avoid sending any MSC_SERIAL event if the value of serial[0] == 0
(which is the case for devices that don't actually report a
serial number), but this is not quite sufficient.
Only the lower 32 bits of the serial get reported to userspace,
so if this portion of the serial is zero then there can still
be problems.

This commit allows the driver to report either the lower 32 bits
if they are non-zero or the upper 32 bits otherwise.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Tatsunosuke Tobita <tatsunosuke.tobita@wacom.com>
Fixes: f85c9dc678a5 ("HID: wacom: generic: Support tool ID and additional tool types")
CC: stable@vger.kernel.org # v4.10
---
 drivers/hid/wacom_wac.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Comments

Jiri Kosina Feb. 13, 2024, 10:40 a.m. UTC | #1 
On Thu, 1 Feb 2024, Tobita, Tatsunosuke wrote:

> From: Tatsunosuke Tobita <tatsunosuke.tobita@wacom.com>
> 
> The xf86-input-wacom driver does not treat '0' as a valid serial
> number and will drop any input report which contains an
> MSC_SERIAL = 0 event. The kernel driver already takes care to
> avoid sending any MSC_SERIAL event if the value of serial[0] == 0
> (which is the case for devices that don't actually report a
> serial number), but this is not quite sufficient.
> Only the lower 32 bits of the serial get reported to userspace,
> so if this portion of the serial is zero then there can still
> be problems.
> 
> This commit allows the driver to report either the lower 32 bits
> if they are non-zero or the upper 32 bits otherwise.
> 
> Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
> Signed-off-by: Tatsunosuke Tobita <tatsunosuke.tobita@wacom.com>
> Fixes: f85c9dc678a5 ("HID: wacom: generic: Support tool ID and additional tool types")
> CC: stable@vger.kernel.org # v4.10

Applied to hid.git#for-6.8/upstream-fixes.
diff mbox series

Patch

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index da8a01fedd39..fbe10fbc5769 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2575,7 +2575,14 @@  static void wacom_wac_pen_report(struct hid_device *hdev,
 				wacom_wac->hid_data.tipswitch);
 		input_report_key(input, wacom_wac->tool[0], sense);
 		if (wacom_wac->serial[0]) {
-			input_event(input, EV_MSC, MSC_SERIAL, wacom_wac->serial[0]);
+			/*
+			 * xf86-input-wacom does not accept a serial number
+			 * of '0'. Report the low 32 bits if possible, but
+			 * if they are zero, report the upper ones instead.
+			 */
+			__u32 serial_lo = wacom_wac->serial[0] & 0xFFFFFFFFu;
+			__u32 serial_hi = wacom_wac->serial[0] >> 32;
+			input_event(input, EV_MSC, MSC_SERIAL, (int)(serial_lo ? serial_lo : serial_hi));
 			input_report_abs(input, ABS_MISC, sense ? id : 0);
 		}