CM9 (Android 4.0 ICS) and deep sleep

I’ve had the problem that the device didn’t want to switch into deep sleep mode if radio was on. What is deep sleep? To make it simple we break it down. Your device has 3 modes. The fisrst is “Screen On and Awake”, “Awake” and “Deep Sleep”. If you use your device it you’re in the first mode and you need a obviously a lot of battery. The second “Awake” means it is doing some background work. Checking for calls, checking Emails, syncing contacts. The last one means it goes for some time into a mode were it uses almost no battery, and this is Deep Sleep. If you don’t do anything and your phone is in your pocket you want that it is in the Deep Sleep mode most of the time.

My HTC Wildfire S didn’t want to go into the “Deep Sleep” mode at all if radio was turned on. It worked with Airplane mode. I thought this has something todo with RIL but I was wrong. Actually it was a bluetooth wakelock. The wakelock “msm_serial_hs_dma” was held all the time. The problem is that the msm7227 platform doesn’t supports quick switch-on/off of the bluetooth module and you need to deactivate it with an overlay else ICS always tries to trigger it.

So adding

<bool name="config_bluetooth_adapter_quick_switch">false</bool>

to overlay/frameworks/base/core/res/res/values/config.xml fixed the problem and the wakelock was gone.