[PATCH 3.14 028/140] HID: core: do not scan constant input report

Greg Kroah-Hartman
2014-05-29T05:36:34Z

From: Benjamin Tissoires <benjamin.tissoires@redhat.com>

commit e24d0d399b2fce71b627043e900ef28283850482 upstream.

The Microsoft Surface Type/Touch Cover 2 is a fancy device which advertised
itself as a multitouch device but with constant input reports.
This way, hid_scan_report() gives the group MULTITOUCH to it, but
hid-multitouch can not handle it due to the constant collection ignored
by hid-input.

To prevent such crap in the future, and while we do not fix this particular
device, make the scan_report coherent with hid-input.c, and ignore constant
input reports.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hid/hid-core.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -718,6 +718,9 @@ static int hid_scan_main(struct hid_pars
case HID_MAIN_ITEM_TAG_END_COLLECTION:
break;
case HID_MAIN_ITEM_TAG_INPUT:
+ /* ignore constant inputs, they will be ignored by hid-input */
+ if (data & HID_MAIN_ITEM_CONSTANT)
+ break;
for (i = 0; i < parser->local.usage_index; i++)
hid_scan_input_usage(parser, parser->local.usage[i]);
break;