Recent ModemManager versions no longer work on the Samsung A5 (Qualcomm
MSM8916) smartphone: MM ends up in an infinite loop trying to probe the
modem over and over again.
Looking at the debug log it seems to be related to a "Slot Status"
indication that comes in during probe time and causes MM to restart
the probing process:
[/dev/wwan0qmi0] Sent generic request (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Register Events" (0x002E)
<< TLV: translated = physical-slot-status
[/dev/wwan0qmi0] Received generic indication (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Slot Status" (0x0048)
<< TLV: translated = { [0] = '[ physical_card_status = 'present', ...
[/dev/wwan0qmi0] Received generic response (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Register Events" (0x002E)
<< TLV: translated = SUCCESS
[modem42] registered for slot status indications
[/dev/wwan0qmi0] Sent generic request (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Get Slot Status" (0x0047)
[modem42] received slot status indication
[modem42] An active slot had a status change, will reprobe the modem
<infinite loop>
The "Slot Status" indication (uim_slot_status_indication_cb) arrives
immediately after starting to listen for the event, which is before
ModemManager has actually loaded the initial slot status in
uim_get_slot_status_ready. In this situation !slot_array_status_equal()
will always cause the modem to reprobe, even though it is not necessary
during the probe phase.
To fix this add a simple check to uim_slot_status_indication_cb() that
ignores the indication if the initial slot status was not loaded yet.
Stephan Gerhold
8d95c82f9c