Hey,
I found out something today. If you play a song in OS X and unplug the AC adapter, there's a short burst of sound from the speaker. Maybe there is something wrong with the power management control of HDA kext file.
I installed Azalia patch and was able to get the volume control (and this weird behaviour).
Here's part of the ioreg output
| | | +-o AppleAzaliaController <class AppleAzaliaController, registered, matched, active, busy 0, retain 8>
| | | | {
| | | | "IOProviderClass" = "IOPCIDevice"
| | | | "IOProbeScore" = 0
| | | | "CFBundleIdentifier" = "com.apple.driver.AppleAzaliaController"
| | | | "IOMatchCategory" = "IODefaultMatchCategory"
| | | | "IOPCIPrimaryMatch" = "0x26688086 0x27d88086 0x284b8086 0x32881106 0x026c10de 0x037110de 0x03e410de 0x03f010de 0x044a10de 0x044b10de 0x437b1002 0x43831002 0x75021039"
| | | | "IOPowerManagement" = {"ChildrenPowerState"=2,"CurrentPowerState"=2}
| | | | "IOClass" = "AppleAzaliaController"
| | | | }
| | | |
| | | +-o IOHDAudioCodecDevice@0 <class IOHDAudioCodecDevice, registered, matched, active, busy 0, retain 6>
| | | | | {
| | | | | "IOHDAudioCodecVendorID" = 299112836
| | | | | "IOHDAudioCodecRevisionID" = 1049600
| | | | | }
| | | | |
| | | | +-o IOHDAudioCodecDriver <class IOHDAudioCodecDriver, !registered, !matched, active, busy 0, retain 5>
| | | | | {
| | | | | "IOProviderClass" = "IOHDAudioCodecDevice"
| | | | | "IOProbeScore" = 0
| | | | | "IOMatchCategory" = "IODefaultMatchCategory"
| | | | | "IOClass" = "IOHDAudioCodecDriver"
| | | | | "CFBundleIdentifier" = "com.apple.iokit.IOHDAudioFamily"
| | | | | }
| | | | |
| | | | +-o IOHDAudioCodecFunction@1 <class IOHDAudioCodecFunction, registered, matched, active, busy 0, retain 6>
| | | | | {
| | | | | "IOHDAudioCodecFunctionSubsystemID" = 397025501
| | | | | "IOHDAudioCodecFunctionGroupType" = 1
| | | | | }
| | | | |
| | | | +-o AppleAzaliaAudioCodecGeneric <class AppleAzaliaAudioCodecGeneric, registered, matched, active, busy 0, retain 10>
| | | | | {
| | | | | "IOProviderClass" = "IOHDAudioCodecFunction"
| | | | | "IOProbeScore" = 0
| | | | | "IOMatchCategory" = "IODefaultMatchCategory"
| | | | | "IOHDAudioCodecFunctionGroupType" = 1
| | | | | "IOClass" = "AppleAzaliaAudioCodecGeneric"
| | | | | "CFBundleIdentifier" = "com.apple.driver.AppleAzaliaAudio"
| | | | | }
| | | | |
| | | | +-o AppleAzaliaAudioDriver <class AppleAzaliaAudioDriver, registered, matched, active, busy 0, retain 6>
| | | | | {
| | | | | "IOProbeScore" = 0
| | | | | "IOAudioDeviceManufacturerName" = "Apple"
| | | | | "InputSampleLatency" = 30
| | | | | "CFBundleIdentifier" = "com.apple.driver.AppleAzaliaAudio"
| | | | | "IOMatchCategory" = "IODefaultMatchCategory"
| | | | | "IOPowerManagement" = {"CurrentPowerState"=1,"DriverChangePowerState"=1}
| | | | | "IOAudioDeviceShortName" = "Built-in"
| | | | | "IOProviderClass" = "AppleAzaliaAudioCodec"
| | | | | "IOAudioDeviceCanBeDefaults" = 7
| | | | | "IOAudioDeviceTransportType" = 1651274862
| | | | | "IOAudioDeviceName" = "Built-in Audio"
| | | | | "IOAudioDeviceModelID" = "AppleAzaliaAudioDriver:Built-in Audio"
| | | | | "SampleOffsetPad" = 0
| | | | | "IOClass" = "AppleAzaliaAudioDriver"
| | | | | "OutputSampleLatency" = 30
| | | | | }
| | | | |
| | | | +-o AppleAzaliaAudioEngineOutput <class AppleAzaliaAudioEngineOutput, registered, matched, active, busy 0, retain 21>
| | | | | {
| | | | | "IOAudioEngineOutputSampleLatency" = 30
| | | | | "IOAudioEngineDescription" = "HD Audio Output"
| | | | | "IOAudioEngineNumActiveUserClients" = 0
| | | | | "IOAudioEngineNumSampleFramesPerBuffer" = 16384
| | | | | "IOAudioEngineSampleOffset" = 32
| | | | | "IOAudioEngineClockDomain" = 87819776
| | | | | "IOAudioEngineState" = 0
| | | | | "IOAudioEngineFlavor" = 1
| | | | | "IOAudioEngineGlobalUniqueID" = "AppleAzaliaAudioEngineOutput:0"
| | | | | "IOAudioSampleRate" = {"IOAudioSampleRateFraction"=0,"IOAudioSampleRateWholeNumber"=44100}
| | | | | "IOAudioEngineInputSampleLatency" = 30
| | | | | "IOGeneralInterest" = "IOCommand is not serializable"
| | | | | }