tools: clarify PermissionError in measure-trackpoint-range

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
(cherry picked from commit ac1d5082fe87c52420720ca46b7862a214c61618)

diff --git a/tools/libinput-measure-trackpoint-range b/tools/libinput-measure-trackpoint-range
index 512978c04074eb4844016a6478f95d3e8cc93d21..40403616868320b9aa338030ec3434f94775cf1f 100755 (executable)
--- a/tools/libinput-measure-trackpoint-range
+++ b/tools/libinput-measure-trackpoint-range
@@ -189,7 +189,7 @@ def main(args):
     except KeyboardInterrupt:
         device.print_summary()
     except (PermissionError, OSError):
-        print("Error: failed to open device")
+        print("Error: failed to open device. Are you running as root?")
     except InvalidDeviceError as e:
         print("Error: {}".format(e))