1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 4c697498fcf9..d0fa6a7e9bc0 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -77,6 +77,8 @@ struct mt_device {
         unsigned last_slot_field;       /* the last field of a slot */
         int last_mt_collection; /* last known mt-related collection */
         __s8 inputmode;         /* InputMode HID feature, -1 if non-existent */
+        __s8 maxcontact_report_id;      /* Maximum Contact Number HID feature,
+                                   -1 if non-existent */
         __u8 num_received;      /* how many contacts we received */
         __u8 num_expected;      /* expected last contact index */
         __u8 maxcontacts;
@@ -242,6 +244,7 @@ static void mt_feature_mapping(struct hid_device *hdev,
                 td->inputmode = field->report->id;
                 break;
         case HID_DG_CONTACTMAX:
+                td->maxcontact_report_id = field->report->id;
                 td->maxcontacts = field->value[0];
                 if (td->mtclass.maxcontacts)
                         /* check if the maxcontacts is given by the class */
@@ -606,6 +609,32 @@ static void mt_set_input_mode(struct hid_device *hdev)
         }
 }
 
+static void mt_set_maxcontacts(struct hid_device *hdev)
+{
+        struct mt_device *td = hid_get_drvdata(hdev);
+        struct hid_report *r;
+        struct hid_report_enum *re;
+        int fieldmax, max;
+
+        if (td->maxcontact_report_id < 0)
+                return;
+
+        if (!td->mtclass.maxcontacts)
+                return;
+
+        re = &hdev->report_enum[HID_FEATURE_REPORT];
+        r = re->report_id_hash[td->maxcontact_report_id];
+        if (r) {
+                max = td->mtclass.maxcontacts;
+                fieldmax = r->field[0]->logical_maximum;
+                max = min(fieldmax, max);
+                if (r->field[0]->value[0] != max) {
+                        r->field[0]->value[0] = max;
+                        usbhid_submit_report(hdev, r, USB_DIR_OUT);
+                }
+        }
+}
+
 static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 {
         int ret, i;
@@ -631,6 +660,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
         }
         td->mtclass = *mtclass;
         td->inputmode = -1;
+        td->maxcontact_report_id = -1;
         td->last_mt_collection = -1;
         hid_set_drvdata(hdev, td);
 
@@ -653,6 +683,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
         ret = sysfs_create_group(&hdev->dev.kobj, &mt_attribute_group);
 
+        mt_set_maxcontacts(hdev);
         mt_set_input_mode(hdev);
 
         return 0;
@@ -665,6 +696,7 @@ fail:
 #ifdef CONFIG_PM
 static int mt_reset_resume(struct hid_device *hdev)
 {
+        mt_set_maxcontacts(hdev);
         mt_set_input_mode(hdev);
         return 0;
 }