Motorola Photon Q: how to solve the signal and battery problems

Some months ago I had worked hard on a "sim-modded" Motorola Photon Q to improve via software the connection 2G/3G and for this I released several updates for the gsm patch to reconfigure the RIL interface to make it correctly work on european gsm networks.

The patch had improved the signal and the performance of data traffic, optimized the switching 2G/3G and accelerated the recovery of the signal after it is lost in a dark area but at a later time I noticed that in areas with very low signal or in long travel during which the phone was forced to quickly change various cell then there were still several problems:

  • question mark in signal icon
  • loss of signal, solvable only with a reboot
  • inability to connect to internet with data packet also if the signal was there, solvable only with a reboot
  • inability to automatically reconnect to the network after losing the signal in a uncovered zone with the subsequent loss of the sim with the message "Unknown Sim", solvable only with a reboot
  • modem crash with new pin sim request
  • modem crash with dumps in these paths:
    • /data/misc/ril/bp-dumps/modem.log
    • /sdcard/bp-dumps/folder_named_with_date_crash/ramdump_modem_fw.bin
    • /sdcard/bp-dumps/folder_named_with_date_crash/ramdump_modem_sw.bin
    • /sdcard/bp-dumps/folder_named_with_date_crash/ramdump_smem.bin
  • fast battery drain caused by modem

For this I realized that further the RIL i had to edit the modem too and this was possible considering that it is a Qualcomm device but in that moment i was not be able to do for lack of time.

Lately I've had a little time off and therefore I dedicated me to the work that I had left open and disabling in the modem the cdma and lte networks and activating an intermediate gsm frequency all the problems that I noticed are promptly disappeared, the phone has a signal identical to that of a native GSM\UMTS phone and the battery life is up to two days.

Here is the way to configure a Motorola Photon Q to correctly work on GSM networks:

  • install the gsm patch to reconfigure the RIL interface
  • correctly configure the radio with the software radio-tool:

radio-tool +uslock -cdma +eugsm –sprlte –vzwlte

  • delete radios cache:
fastboot erase modemst1
fastboot erase modemst2

The software radio-tool has been wrote by mionica (here the source code) and it has to be used as superuser in this way:

radio-tool [dbg] [{+|-}opt [...]]

where opt is one of:

  • uslock - US GSM lockout
  • cdma - CDMA bands (CDMA800 / CDMA1800 / CDMA2000 1xEV-DO)

  • usgsm - US GSM/HSPA bands (GSM850, GSM1900, WCDMA850, WCDMA1900)

  • eugsm - EU GSM/HSPA bands (GSM900, GSM1800, WCDMA900, WCDMA2100)

  • sprlte - Sprint LTE (LTE25, 1900)

  • vzwlte - Verizon LTE (LTE13, 700)