diff options
Diffstat (limited to 'drivers/hid/hid-input.c')
| -rw-r--r-- | drivers/hid/hid-input.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c index 66763546df15..1419f8bd11ba 100644 --- a/drivers/hid/hid-input.c +++ b/drivers/hid/hid-input.c @@ -1083,6 +1083,23 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct return; } + /* + * Ignore reports for absolute data if the data didn't change. This is + * not only an optimization but also fixes 'dead' key reports. Some + * RollOver implementations for localized keys (like BACKSLASH/PIPE; HID + * 0x31 and 0x32) report multiple keys, even though a localized keyboard + * can only have one of them physically available. The 'dead' keys + * report constant 0. As all map to the same keycode, they'd confuse + * the input layer. If we filter the 'dead' keys on the HID level, we + * skip the keycode translation and only forward real events. + */ + if (!(field->flags & (HID_MAIN_ITEM_RELATIVE | + HID_MAIN_ITEM_BUFFERED_BYTE)) && + (field->flags & HID_MAIN_ITEM_VARIABLE) && + usage->usage_index < field->maxusage && + value == field->value[usage->usage_index]) + return; + /* report the usage code as scancode if the key status has changed */ if (usage->type == EV_KEY && !!test_bit(usage->code, input->key) != value) input_event(input, EV_MSC, MSC_SCAN, usage->hid); |