[PATCH 3.16 025/217] HID: core: do not scan reports if the group is already set

[Ben Hutchings]

3.16.35-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>

commit 9578f41aeaee5010384f4f8484da1566e2ce4901 upstream.

This allows the transport layer (I have in mind hid-logitech-dj and uhid)
to set the group before it is added to the hid bus. This way, it can
bypass the hid_scan_report() call, and choose in advance which driver
will handle the newly created hid device.

Signed-off-by: Benjamin Tisssoires <benjamin.tissoires@xxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/hid/hid-core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2532,7 +2532,8 @@ int hid_add_device(struct hid_device *hd
 	 * Scan generic devices for group information
 	 */
 	if (hid_ignore_special_drivers ||
-	    !hid_match_id(hdev, hid_have_special_driver)) {
+	    (!hdev->group &&
+	     !hid_match_id(hdev, hid_have_special_driver))) {
 		ret = hid_scan_report(hdev);
 		if (ret)
 			hid_warn(hdev, "bad device descriptor (%d)\n", ret);