// Workaround for Samsung CDMA "ring of death" bug:
//
// Symptom: As soon as the phone receives notice of an incoming call, an
// audible "old fashioned ring" is emitted through the earpiece and
// persists through the duration of the call, or until reboot if the call
// isn't answered.
//
// Background: The CDMA telephony stack implements a number of "signal info
// tones" that are locally generated by ToneGenerator and mixed into the
// voice call path in response to radio RIL_UNSOL_CDMA_INFO_REC requests.
// One of these tones, IS95_CONST_IR_SIG_IS54B_L, is requested by the
// radio just prior to notice of an incoming call when the voice call
// path is muted. CallNotifier is responsible for stopping all signal
// tones (by "playing" the TONE_CDMA_SIGNAL_OFF tone) upon receipt of a
// "new ringing connection", prior to unmuting the voice call path.
//
// Problem: CallNotifier's incoming call path is designed to minimize
// latency to notify users of incoming calls ASAP. Thus,
// SignalInfoTonePlayer requests are handled asynchronously by spawning a
// one-shot thread for each. Unfortunately the ToneGenerator API does
// not provide a mechanism to specify an ordering on requests, and thus,
// unexpected thread interleaving may result in ToneGenerator processing
// them in the opposite order that CallNotifier intended. In this case,
// playing the "signal off" tone first, followed by playing the "old
// fashioned ring" indefinitely.
//
// Solution: An API change to ToneGenerator is required to enable
// SignalInfoTonePlayer to impose an ordering on requests (i.e., drop any
// request that's older than the most recent observed). Such a change,
// or another appropriate fix should be implemented in AOSP first.
//
// Workaround: Intercept RIL_UNSOL_CDMA_INFO_REC requests from the radio,
// check for a signal info record matching IS95_CONST_IR_SIG_IS54B_L, and
// drop it so it's never seen by CallNotifier. If other signal tones are
// observed to cause this problem, they should be dropped here as well.
@Override
protected void notifyRegistrantsCdmaInfoRec(CdmaInformationRecords infoRec) {
final int response = RIL_UNSOL_CDMA_INFO_REC;
if (infoRec.record instanceof CdmaSignalInfoRec) {
CdmaSignalInfoRec sir = (CdmaSignalInfoRec) infoRec.record;
if (sir != null
&& sir.isPresent
&& sir.signalType == SignalToneUtil.IS95_CONST_IR_SIGNAL_IS54B
&& sir.alertPitch == SignalToneUtil.IS95_CONST_IR_ALERT_MED
&& sir.signal == SignalToneUtil.IS95_CONST_IR_SIG_IS54B_L) {
Rlog.d(
RILJ_LOG_TAG,
"Dropping \""
+ responseToString(response)
+ " "
+ retToString(response, sir)
+ "\" to prevent \"ring of death\" bug.");
return;
}
}
super.notifyRegistrantsCdmaInfoRec(infoRec);
}
