HID: core: move Usage Page concatenation to Main item

As seen on some USB wireless keyboards manufactured by Primax, the HID
parser was using some assumptions that are not always true. In this case
it's s the fact that, inside the scope of a main item, an Usage Page
will always precede an Usage.

The spec is not pretty clear as 6.2.2.7 states "Any usage that follows
is interpreted as a Usage ID and concatenated with the Usage Page".
While 6.2.2.8 states "When the parser encounters a main item it
concatenates the last declared Usage Page with a Usage to form a
complete usage value." Being somewhat contradictory it was decided to
match Window's implementation, which follows 6.2.2.8.

In summary, the patch moves the Usage Page concatenation from the local
item parsing function to the main item parsing function.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Terry Junge <terry.junge@poly.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/hid.h b/include/linux/hid.h
index f9707d1dcb58..ac0c70b4ce10 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -417,6 +417,7 @@ struct hid_global {
 
 struct hid_local {
 	unsigned usage[HID_MAX_USAGES]; /* usage array */
+	u8 usage_size[HID_MAX_USAGES]; /* usage size array */
 	unsigned collection_index[HID_MAX_USAGES]; /* collection index array */
 	unsigned usage_index;
 	unsigned usage_minimum;