Input: xen-kbdfront - fix mouse getting stuck after save/restore

Mouse gets "stuck" after restore of PV guest but buttons are in working
condition.

If driver has been configured for ABS coordinates at start it will get
XENKBD_TYPE_POS events and then suddenly after restore it'll start getting
XENKBD_TYPE_MOTION events, that will be dropped later and they won't get
into user-space.

Regression was introduced by hunk 5 and 6 of
5ea5254aa0ad269cfbd2875c973ef25ab5b5e9db
("Input: xen-kbdfront - advertise either absolute or relative
coordinates").

Driver on restore should ask xen for request-abs-pointer again if it is
available. So restore parts that did it before 5ea5254.

Acked-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
[v1: Expanded the commit description]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
index 7077f9bf5ead..62bae99424e6 100644
--- a/drivers/input/misc/xen-kbdfront.c
+++ b/drivers/input/misc/xen-kbdfront.c
@@ -303,7 +303,7 @@ static void xenkbd_backend_changed(struct xenbus_device *dev,
                                    enum xenbus_state backend_state)
 {
         struct xenkbd_info *info = dev_get_drvdata(&dev->dev);
-        int val;
+        int ret, val;
 
         switch (backend_state) {
         case XenbusStateInitialising:
@@ -316,6 +316,17 @@ static void xenkbd_backend_changed(struct xenbus_device *dev,
 
         case XenbusStateInitWait:
 InitWait:
+                ret = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+                                   "feature-abs-pointer", "%d", &val);
+                if (ret < 0)
+                        val = 0;
+                if (val) {
+                        ret = xenbus_printf(XBT_NIL, info->xbdev->nodename,
+                                            "request-abs-pointer", "1");
+                        if (ret)
+                                pr_warning("xenkbd: can't request abs-pointer");
+                }
+
                 xenbus_switch_state(dev, XenbusStateConnected);
                 break;