From: Jason Gerecke <jason.gerecke@xxxxxxxxx>
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@xxxxxxxxx>
Tested-by: Joshua Dickens <joshua.dickens@xxxxxxxxx>
Fixes: 6d09085b38e5 ("HID: wacom: Adding Support for new usages")
---
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 74258a78d0408..cef08737a6240 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2512,9 +2512,14 @@ 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;
}
--
2.46.0
