[Sugar-devel] [PATCH v2] Avoid "Cannot unfreeze the DCON"

[James Cameron]

Sugar asks olpc-powerd to unfreeze the display once startup is
complete.  On platforms without olpc-powerd, this causes:

	ERROR dbus.proxies: Introspect error on
	org.freedesktop.ohm:/org/freedesktop/ohm/Keystore:
	dbus.exceptions.DBusException:
	org.freedesktop.DBus.Error.ServiceUnknown: The name
	org.freedesktop.ohm was not provided by any .service files
	ERROR root: Cannot unfreeze the DCON

Remove this logging, by detecting powerd before resolving the interface.

Remove the DCON concept from main.py, by changing method names, so that
the implementation details are hidden in model/screen.py
---
v1: was [PATCH] avoid reporting missing DCON
v2: incorporate feedback from Jerry.

 src/jarabe/main.py         |  8 ++++----
 src/jarabe/model/screen.py | 27 +++++++++++++++------------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/src/jarabe/main.py b/src/jarabe/main.py
index 6fcbaaa..4a9fb29 100755
--- a/src/jarabe/main.py
+++ b/src/jarabe/main.py
@@ -74,9 +74,9 @@ _window_manager_started = False
 _starting_desktop = False
 
 
-def unfreeze_dcon_cb():
-    logging.debug('STARTUP: unfreeze_dcon_cb')
-    screen.set_dcon_freeze(0)
+def unfreeze_screen_cb():
+    logging.debug('STARTUP: unfreeze_screen_cb')
+    screen.unfreeze(0)
 
 
 def setup_frame_cb():
@@ -393,7 +393,7 @@ def main():
 
     # this must be added early, so that it executes and unfreezes the screen
     # even when we initially get blocked on the intro screen
-    GLib.idle_add(unfreeze_dcon_cb)
+    GLib.idle_add(unfreeze_screen_cb)
 
     GLib.idle_add(setup_cursortracker_cb)
     sound.restore()
diff --git a/src/jarabe/model/screen.py b/src/jarabe/model/screen.py
index f70bda1..bdf302a 100644
--- a/src/jarabe/model/screen.py
+++ b/src/jarabe/model/screen.py
@@ -23,23 +23,26 @@ _HARDWARE_MANAGER_INTERFACE = 'org.freedesktop.ohm.Keystore'
 _HARDWARE_MANAGER_SERVICE = 'org.freedesktop.ohm'
 _HARDWARE_MANAGER_OBJECT_PATH = '/org/freedesktop/ohm/Keystore'
 
-_ohm_service = None
+POWERD_FLAG_DIR = '/etc/powerd/flags'
+
+
+def using_powerd():
+    return os.access(POWERD_FLAG_DIR, os.W_OK)
 
 
 def _get_ohm():
-    global _ohm_service
-    if _ohm_service is None:
-        bus = dbus.SystemBus()
-        proxy = bus.get_object(_HARDWARE_MANAGER_SERVICE,
-                               _HARDWARE_MANAGER_OBJECT_PATH,
-                               follow_name_owner_changes=True)
-        _ohm_service = dbus.Interface(proxy, _HARDWARE_MANAGER_INTERFACE)
+    bus = dbus.SystemBus()
+    proxy = bus.get_object(_HARDWARE_MANAGER_SERVICE,
+                           _HARDWARE_MANAGER_OBJECT_PATH,
+                           follow_name_owner_changes=True)
+    return dbus.Interface(proxy, _HARDWARE_MANAGER_INTERFACE)
 
-    return _ohm_service
 
+def unfreeze():
+    if not using_powerd():
+        return
 
-def set_dcon_freeze(frozen):
     try:
-        _get_ohm().SetKey('display.dcon_freeze', frozen)
+        _get_ohm().SetKey('display.dcon_freeze', 0)
     except dbus.DBusException:
-        logging.error('Cannot unfreeze the DCON')
+        pass
-- 
1.8.3.2