[Galaxy S 4 General] -sandro-:
Hello,

as you may or may not know fast dormancy is by now a mature technology implemented by all major networks worldwide. It involves 3G (HSPA) technology only and it allows the phone AND the network to keep the connection on using different levels of state (RRC) so that when you finish transferring data at high speed the state goes to a lower energy one or even idle using much less power, saving battery life significantly.

It has been explained by XDA website 2 years ago, you can also find more info on wikipedia.

What's the point of this topic? With my i9505 International I've always used Google Edition ROMs since the first edition was released. Battery life has always been fine while using 3G data on standby.

When I upgraded to KitKat Google Edition I noticed the battery would drain much, much quicker (when the screen is off mainly). I got used to it that I assumed it was how things worked until I ended up reading about people with much battery life on 3G and KitKat (but CM11 or AOSP) so I started investigating and trying different ROMs/configurations (I asked devs on their respective threads but I have been completely boycotted! :( ). At the end I concluded fast dormancy was not working (on the phone part) in anyway on KitKat ROMs made by Samsung.

How do you know if FD is active on the device?

- install apps to detect wakelocks like BetterBatteryStats (you don't need root)

- turn on 3G data and disable WiFi

- keep the screen off for about 1 minute (make sure you're not downloading anything)

- turn on the screen on check "kernel wakelocks". If you have "fast_dormancy" anywhere in the list then it's on otherwise it is not active

What ROMs did you test and how?

This is what I did: I made sure to have the same configuration and apps on every test, same location and signal strength.

I charged the phone to 100%, turn on 3G data, unplugged and left it idling with sync on for 4 hours. I noticed (via betterbatterystats logs) that with fast dormancy off I would lose about 2.5%/h, while with fast dormancy on the drop would be about 0.7%/h!!

And let's not talk about when you move around or drive, for instance with FD off with my usual drive to class I've always lost 3-4% in 15 minutes, I mean ALWAYS. With FD on the battery wouldn't move at all! That is a HUGE difference!

The ultimate test for me was a real life test. I went studying for two consecutive days at college in the same spot using the phone the same way (browsing, tapatalk, facebook messenger), with FD off I would come back home after using the screen for 1h30m at about 15% (mainly because I would lose power just on stand-by!) but FD on repeating the same steps the following day with FD on I went home at the same time and after using the screen for 2h20m I still had 45% of battery, WOW!

ROMs where FD works:

- 4.2.2, 4.3 TW

- 4.2.2., 4.3 GE (untouched and customized)

- CM10.2, CM11

- AOSP 4.4.2 ROMs

ROMs where FD doesn't work:

4.4.2 GE (untouched and customized)

4.4.2 TW (leak)

I used only one modem during these tests, the latest from the KITKAT leak.

What have you tried to force it?

Well I can tell you for sure that ro.ril.fast.dormancy.rule has no effect on TW/GE ROMs, I also tried to change the database as described here http://www.androidnz.net/2012/06/at-your-own-risk-how-to-disable-fast.html to set it to ON but you should know that FD on every ROM is on by default. I have no proof of this but with FD off even if your network seems to go to lower energy states on the network side (you can see all this using Samsung Service Mode), on the phone side the radio keeps using a lot of power as if it remains "active" thus draining battery like a b*tch :D

So has Samsung forgotten to include this feature? What do you think?

Also do you know where I can ask support for this to be fixed? Should I ask Google on the play store (even if I don't technically have a GPE phone!) or via Samsung website even if it's not sold on their site? Even worse KK TW is not even out yet officially.