HID: wacom: Do not warn about dropped packets for first packet

[ Upstream commit 84aecf2d251a3359bc78b7c8e58f54b9fc966e89 ]

The driver currently assumes that the first sequence number it will see
is going to be 0. This is not a realiable assumption and can break if,
for example, the tablet has already been running for some time prior to
the kernel driver connecting to the device. This commit initializes the
expected sequence number to -1 and will only print the "Dropped" warning
the it has been updated to a non-negative value.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Tested-by: Joshua Dickens <joshua.dickens@wacom.com>
Fixes: 6d09085b38e5 ("HID: wacom: Adding Support for new usages")
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 8cf82a5f3a5bf7e893df0b13f769670c1429d5fb..7660f62e6c1f2352e41b8a2c8d7d957538567ae4 100644 (file)
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2368,6 +2368,9 @@ static void wacom_wac_pen_usage_mapping(struct hid_device *hdev,
                wacom_map_usage(input, usage, field, EV_KEY, BTN_STYLUS3, 0);
                features->quirks &= ~WACOM_QUIRK_PEN_BUTTON3;
                break;
+       case WACOM_HID_WD_SEQUENCENUMBER:
+               wacom_wac->hid_data.sequence_number = -1;
+               break;
        }
 }
 
@@ -2492,7 +2495,8 @@ 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) {
+               if (wacom_wac->hid_data.sequence_number != value &&
+                   wacom_wac->hid_data.sequence_number >= 0) {
                        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);

diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
index 6ec499841f70959d8a6cc6e3ef2e5c21cddc9761..e6443740b462fdfa857e69012dc2b9c603768f2b 100644 (file)
--- a/drivers/hid/wacom_wac.h
+++ b/drivers/hid/wacom_wac.h
@@ -324,7 +324,7 @@ struct hid_data {
        int bat_connected;
        int ps_connected;
        bool pad_input_event_flag;
-       unsigned short sequence_number;
+       int sequence_number;
        ktime_t time_delayed;
 };