HID: core: fix grouping by application

commit f07b3c1da92d ("HID: generic: create one input report per
application type") was effectively the same as MULTI_INPUT:
hidinput->report was never set, so hidinput_match_application()
always returned null.

Fix that by testing against the real application.

Note that this breaks some old eGalax touchscreens that expect MULTI_INPUT
instead of HID_QUIRK_INPUT_PER_APP. Enable this quirk for backward
compatibility on all non-Win8 touchscreens.

link: https://bugzilla.kernel.org/show_bug.cgi?id=200847
link: https://bugzilla.kernel.org/show_bug.cgi?id=200849
link: https://bugs.archlinux.org/task/59699
link: https://github.com/NixOS/nixpkgs/issues/45165

Cc: stable@vger.kernel.org # v4.18+
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

3 files changed, 6 insertions, 2 deletions

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index ac201817a2dd..a481eaf39e88 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1582,6 +1582,7 @@ static struct hid_input *hidinput_allocate(struct hid_device *hid,
         input_dev->dev.parent = &hid->dev;
 
         hidinput->input = input_dev;
+        hidinput->application = application;
         list_add_tail(&hidinput->list, &hid->inputs);
 
         INIT_LIST_HEAD(&hidinput->reports);
@@ -1677,8 +1678,7 @@ static struct hid_input *hidinput_match_application(struct hid_report *report)
         struct hid_input *hidinput;
 
         list_for_each_entry(hidinput, &hid->inputs, list) {
-                if (hidinput->report &&
-                    hidinput->report->application == report->application)
+                if (hidinput->application == report->application)
                         return hidinput;
         }
 
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 88da991ef256..da954f3f4da7 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -1697,6 +1697,9 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
          */
         hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
 
+        if (id->group != HID_GROUP_MULTITOUCH_WIN_8)
+                hdev->quirks |= HID_QUIRK_MULTI_INPUT;
+
         timer_setup(&td->release_timer, mt_expired_timeout, 0);
 
         ret = hid_parse(hdev);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 834e6461a690..d44a78362942 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -526,6 +526,7 @@ struct hid_input {
         const char *name;
         bool registered;
         struct list_head reports;       /* the list of reports */
+        unsigned int application;       /* application usage for this input */
 };
 
 enum hid_type {