"Wake reason ?" issue is still not resolved for me after the recently released MBA firmware upgrade. Avast is not installed.
Ubuntu here I come...
16/06/14 04:52:40.000 kernel[0]: AppleThunderboltNHI::prePCIWake - power up complete - took 673 us
16/06/14 04:52:40.000 kernel[0]: AppleThunderboltHAL::earlyWake - complete - took 0 milliseconds
16/06/14 04:53:05.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:53:05.000 kernel[0]: Wake reason: ?
16/06/14 04:53:05.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:53:05.000 kernel[0]: AppleCamIn::wakeEventHandlerThread
16/06/14 04:53:05.000 kernel[0]: AppleHSSPIController::HandleMessage Device Wake by Host
16/06/14 04:53:05.000 kernel[0]: AppleThunderboltNHI::prePCIWake - power up complete - took 180466 us
16/06/14 04:53:05.000 kernel[0]: AppleThunderboltHAL::earlyWake - complete - took 2 milliseconds
16/06/14 04:53:05.000 kernel[0]: ARPT: 111987.630522: AirPort_Brcm43xx::powerChange: System Wake - Full Wake/ Dark Wake / Maintenance wake
16/06/14 04:53:05.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:53:05.000 kernel[0]: AppleCamIn::wakeEventHandlerThread
16/06/14 04:53:10.000 kernel[0]: AppleCamIn::handleWakeEvent_gated
16/06/14 04:53:10.000 kernel[0]: AppleCamIn::handleWakeEvent_gated
16/06/14 04:53:57.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:53:58.000 kernel[0]: AppleThunderboltNHI::prePCIWake - power up complete - took 673 us
16/06/14 04:53:58.000 kernel[0]: AppleThunderboltHAL::earlyWake - complete - took 0 milliseconds
16/06/14 04:54:23.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:54:23.000 kernel[0]: Wake reason: ?
16/06/14 04:54:23.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:54:23.000 kernel[0]: AppleCamIn::wakeEventHandlerThread
16/06/14 04:54:23.000 kernel[0]: AppleHSSPIController::HandleMessage Device Wake by Host
16/06/14 04:54:23.000 kernel[0]: AppleThunderboltNHI::prePCIWake - power up complete - took 181174 us
16/06/14 04:54:23.000 kernel[0]: AppleThunderboltHAL::earlyWake - complete - took 2 milliseconds
16/06/14 04:54:23.000 kernel[0]: ARPT: 112066.069968: AirPort_Brcm43xx::powerChange: System Wake - Full Wake/ Dark Wake / Maintenance wake
16/06/14 04:54:23.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:54:23.000 kernel[0]: AppleCamIn::wakeEventHandlerThread
16/06/14 04:54:28.000 kernel[0]: AppleCamIn::handleWakeEvent_gated
16/06/14 04:54:28.000 kernel[0]: AppleCamIn::handleWakeEvent_gated
16/06/14 04:55:15.000 kernel[0]: AppleCamIn::systemWakeCall - messageType = 0xE0000340
16/06/14 04:55:16.000 kernel[0]: AppleThunderboltNHI::prePCIWake - power up complete - took 703 us
16/06/14 04:55:16.000 kernel[0]: AppleThunderboltHAL::earlyWake - complete - took 0 milliseconds