HID: hid-multitouch: ensure slots are initialized

In case a device does not provide the feature "Maximum Contact Count",
or set it at 0, the maxcontacts field may be at 0 while calling
input_mt_init_slots.

This patch ensures that hid-multitouch will allways report
ABS_MT_SLOT and ABS_MT_TRACKING_ID to the user space.

This corrects a bug found with some Ilitek devices that has been
integrated in 3.0-rc0.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 0b2dcd0ee591..386765654cf6 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -271,6 +271,8 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                         }
                         return 1;
                 case HID_DG_CONTACTID:
+                        if (!td->maxcontacts)
+                                td->maxcontacts = MT_DEFAULT_MAXCONTACT;
                         input_mt_init_slots(hi->input, td->maxcontacts);
                         td->last_slot_field = usage->hid;
                         td->last_field_index = field->index;
@@ -547,9 +549,6 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
         if (ret)
                 goto fail;
 
-        if (!td->maxcontacts)
-                td->maxcontacts = MT_DEFAULT_MAXCONTACT;
-
         td->slots = kzalloc(td->maxcontacts * sizeof(struct mt_slot),
                                 GFP_KERNEL);
         if (!td->slots) {