[PATCH evdev 1/2] Force x/y axes to exist on devices with any other axes (#44655)

[Peter Hutterer]

Too much in the server relies on x/y to exist and to be axes 0 and 1. So if
any relative axes exist, initialize REL_X/Y or ABS_X/Y as well.

For servers up to 1.11: a scrollwheel-only device now has relative axes
where it only had buttons before.

For servers 1.12 or later: the device now has x/y in addition to the scroll
axes.

X.Org Bug 44655 <http://bugs.freedesktop.org/show_bug.cgi?id=44655>

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/evdev.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 43 insertions(+), 0 deletions(-)

diff --git a/src/evdev.c b/src/evdev.c
index 989a255..68e3c75 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -1958,6 +1958,38 @@ EvdevGrabDevice(InputInfoPtr pInfo, int grab, int ungrab)
     return TRUE;
 }
 
+/**
+ * Some devices only have other axes (e.g. wheels), but we
+ * still need x/y for these. The server relies on devices having
+ * x/y as axes 0/1 and core/XI 1.x clients expect it too (#44655)
+ */
+static void
+EvdevForceXY(InputInfoPtr pInfo, int mode)
+{
+    EvdevPtr pEvdev = pInfo->private;
+
+    xf86IDrvMsg(pInfo, X_INFO, "Forcing %s x/y axes to exist.\n",
+                (mode == Relative) ? "relative" : "absolute");
+
+    if (mode == Relative)
+    {
+        EvdevSetBit(pEvdev->rel_bitmask, REL_X);
+        EvdevSetBit(pEvdev->rel_bitmask, REL_Y);
+    } else if (mode == Absolute)
+    {
+        EvdevSetBit(pEvdev->abs_bitmask, ABS_X);
+        EvdevSetBit(pEvdev->abs_bitmask, ABS_Y);
+        pEvdev->absinfo[ABS_X].minimum = 0;
+        pEvdev->absinfo[ABS_X].maximum = 1000;
+        pEvdev->absinfo[ABS_X].value = 0;
+        pEvdev->absinfo[ABS_X].resolution = 0;
+        pEvdev->absinfo[ABS_Y].minimum = 0;
+        pEvdev->absinfo[ABS_Y].maximum = 1000;
+        pEvdev->absinfo[ABS_Y].value = 0;
+        pEvdev->absinfo[ABS_Y].resolution = 0;
+    }
+}
+
 static int
 EvdevProbe(InputInfoPtr pInfo)
 {
@@ -2043,6 +2075,8 @@ EvdevProbe(InputInfoPtr pInfo)
             pEvdev->num_buttons = num_buttons;
         }
 
+        EvdevForceXY(pInfo, Relative);
+
         if (!ignore_rel)
         {
             xf86IDrvMsg(pInfo, X_PROBED, "Found relative axes\n");
@@ -2116,7 +2150,16 @@ EvdevProbe(InputInfoPtr pInfo)
                     pEvdev->flags |= EVDEV_TOUCHSCREEN;
                     pEvdev->flags |= EVDEV_BUTTON_EVENTS;
             }
+        } else {
+#ifdef MULTITOUCH
+            if (!EvdevBitIsSet(pEvdev->abs_bitmask, ABS_MT_POSITION_X) ||
+                !EvdevBitIsSet(pEvdev->abs_bitmask, ABS_MT_POSITION_Y))
+#endif
+                EvdevForceXY(pInfo, Absolute);
         }
+
+
+
     }
 
     for (i = 0; i < BTN_MISC; i++) {
-- 
1.7.7.5