HID: wacom: Support sequence numbers smaller than 16-bit

BugLink: https://bugs.launchpad.net/bugs/2089340

[ Upstream commit 359673e ]

The current dropped packet reporting assumes that all sequence numbers
are 16 bits in length. This results in misleading "Dropped" messages if
the hardware uses fewer bits. For example, if a tablet uses only 8 bits
to store its sequence number, once it rolls over from 255 -> 0, the
driver will still be expecting a packet "256". This patch adjusts the
logic to reset the next expected packet to logical_minimum whenever
it overflows beyond logical_maximum.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Tested-by: Joshua Dickens <joshua.dickens@wacom.com>
Fixes: 6d09085 ("HID: wacom: Adding Support for new usages")
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Portia Stephens <portia.stephens@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: jigpu

drivers/hid/wacom_wac.c

@@ -2492,9 +2492,14 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 		wacom_wac->hid_data.barrelswitch3 = value;
 		return;
 	case WACOM_HID_WD_SEQUENCENUMBER:
-		if (wacom_wac->hid_data.sequence_number != value)
-			hid_warn(hdev, "Dropped %hu packets", (unsigned short)(value - wacom_wac->hid_data.sequence_number));
+		if (wacom_wac->hid_data.sequence_number != value) {
+			int sequence_size = field->logical_maximum - field->logical_minimum + 1;
+			int drop_count = (value - wacom_wac->hid_data.sequence_number) % sequence_size;
+			hid_warn(hdev, "Dropped %d packets", drop_count);
+		}
 		wacom_wac->hid_data.sequence_number = value + 1;
+		if (wacom_wac->hid_data.sequence_number > field->logical_maximum)
+			wacom_wac->hid_data.sequence_number = field->logical_minimum;
 		return;
 	}