From 359673ea3a203611b4f6d0f28922a4b9d2cfbcc8 Mon Sep 17 00:00:00 2001 From: Jason Gerecke Date: Mon, 9 Sep 2024 13:32:07 -0700 Subject: [PATCH] HID: wacom: Support sequence numbers smaller than 16-bit 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 Tested-by: Joshua Dickens Fixes: 6d09085b38e5 ("HID: wacom: Adding Support for new usages") Signed-off-by: Jiri Kosina --- drivers/hid/wacom_wac.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c index 36010c515f39c..22b0d281ff5ca 100644 --- a/drivers/hid/wacom_wac.c +++ b/drivers/hid/wacom_wac.c @@ -2510,9 +2510,14 @@ 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; }