MB525 (CM7 stable) "soft dead" (cannot call) after running for some time

Hello,
I recently flashed CM7 stable, and very happy that the cold-rebooting problem disappeared. But a new problem arises: After some time (several hours maybe) the phone got "dead" silently, i.e. cannot call (just dialing constantly) or receive call (got "shut down" prompt). But the signal display shows good (-71~-51dbm). The system is relatively clean, and killing running services that can be killed do not help (only settings, maps, google play services, android keyboard cannot be killed). After a reboot it gets work again. What should I do to troubleshoot?

more findings; CM7 bug?

Rawwr said:

do a clean install dude,
or try wipe data,
if that doesnt help

i suggest u to install CM9 u will get HWA on ur phone

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Click to collapse

Reinstalling is the last thing I will do, since I have found something that may be relevant. When the error appeared, *#*#4636#*#* testing mode -> phone information will show "preferred network type" as "WCDMA preferred". Since I only have a GSM SIM card without 3G function, that may be the cause. But that cannot be changed when the error occurs, i.e., change that to "GSM only", quit the setting, re-enter, and it have reverted to "WCDMA preferred" automatically. Before the error occurs, that setting can be switched normally.

In settings->wireless & networks->mobile network settings, I have always set "GSM only" in network preferences, and ticked "use only 2G networks". When the error occurs, "GSM only" in network preferences is still there, but "use only 2G networks" is unticked automatically, and cannot be changed either, i.e. tick it, quit the setting, re-enter, and it have reverted to unticked status automatically.

The error will not recover itself; only re-booting can solve the error (switch airplane mode do not help because airplane mode switching also do not work when error occurs). I also found that when that error occurs, battery drains very quickly ( lost 40% one night).

Is this a known bug of CM7 or android? I googled and see lots of similar complains.

I do live in a area with unstable signal. Just now I observed a sudden signal dropping (from -73 to -113dbm) and then phone reconnected successfully (back to -77dbm). I checked *#*#4636#*#* testing -> phone information immediately, the "preferred network type" has been changed from "GSM only" to "GSM auto (PRL)", and in settings->wireless & networks->mobile network settings, "use only 2G networks" has been un-ticked again. But the phone can still work normally in this state. And I know if next time the "preferred network type" be changed to "WCDMA preferred", then I have to re-boot again.

wcdma perferred again

I cannot dial again. The signal strength is -57dbm (even better?!). It just keep dialing and never ends. Even if I tap End button, it will keep "hanging up" but cannot hang up. As expected, "preferred network type" has been changed to "wcdma perferred" again, and "use only 2G networks" has been un-ticked again. How can I fix them?

Rawwr said:

even i flashed cm7 didnt faced such problem,
did u try the baseband switcher ?
try it once
if not
flash an sbf
and install msginger2 or mokee0S or Rabbit Rom for ur device

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Click to collapse

Rebooting again... Yes I have tried baeband switching for dozens of times before I realized that "WCDMA preferred" problem may be the real culprit. I have tried ms2ginger before CM7, but it did not solve another problem: reboot when cold, so I did not test it much. And, aren't they based on CM? They are likely to have same problem.

I think maybe because the GSM signal is poor, after it loses the signal and tries to reconnect, it finds a better WCDMA signal from another provider and got allured sticking on it .. Sounds un-logical.

I hope there's some guidance that can fix that network preference setting to GSM only, and the problem will be sure to solve.

I find some information about Getril, which detect whether your baseband matches RIL, but it's for other phone models and cannot run on Defy. Does Defy have such RIL problem too?

Battery usage picture

Mainly the problem occurs at home, for the signal is poorer in my home. When I go to work the phone could last longer. The attached picture is typical: Roughly the former 2/3 of the curve is night at home, and the later 1/3 is day at work. The battery drops more quickly at home than work. At night, wakelock is normal, but CPU is running at 300MHz all the time. Only in the later 1/3 CPU can go to deep sleep. At night the signal shows green (it's actually WCDMA signal I think), but the phone cannot make or receive calls.