SabreSD-6SX第一次启动Android|SabreSD-6SX第一次启动Android RTC时间无法保存 SabreSD-6SX第一次启动AndroidRTC时

在Android系统download后第一次启动，imx6sx-sabresd 板子改时间没办法保存到RTC中，导致下一次启动后，时间依然是RTC中初始值。之后再次改时间是可以成功保存到RTC中，也不会再出现时间无法保存问题。
第一次启动改时间时打开logcat会出现下面的错误log：

11-05 00:01:36.291508920 D AlarmManagerService: Setting time of day to sec=1194236700 11-05 04:25:00.000508920 W AlarmManagerService: Unable to set rtc to 1194236700: No such device 11-05 04:25:00.026508508 D ConditionProviders.SCP: onReceive android.intent.action.TIME_SET 11-05 04:25:00.034508508 D ConditionProviders.SCP: notifyCondition condition://android/schedule?days=6.7&start=23.30&end=10.0&exitAtAlarm=false STATE_FALSE reason=!meetsSchedule 11-05 04:25:00.035508508 D ConditionProviders.SCP: notifyCondition condition://android/schedule?days=1.2.3.4.5&start=22.0&end=7.0&exitAtAlarm=false STATE_TRUE reason=meetsSchedule 11-05 04:25:00.037508508 D ConditionProviders.SCP: Scheduling evaluate for Mon Nov 05 07:00:00 GMT+00:00 2007 (1194246000000), in +2h34m59s974ms, now=Mon Nov 05 04:25:00 GMT+00:00 2007 (1194236700026) 11-05 04:25:00.062737768 D OpenGLRenderer: endAllActiveAnimators on 0x8bbe5200 (RippleDrawable) with handle 0x8bc67bc0 11-05 04:25:00.111508519 W InputMethodManagerService: Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@e5da2bf attribute=null, token = android.os.BinderProxy@ec6ec1b 11-05 04:25:00.218921921 I Periodic: Executing periodic callback for HOUR because the time changed 11-05 04:25:00.314921921 I AlarmClock: AlarmInitReceiver android.intent.action.TIME_SET 11-05 04:25:00.491508520 I UsageStatsService: Time changed in UsageStats by 15803 seconds 11-05 04:25:00.491508520 I UsageStatsService: User[0] Flushing usage stats to disk 11-05 04:25:00.583508520 I UsageStatsDatabase: Time changed by +4h23m23s709ms. files deleted: 0 files moved: 4 11-05 04:25:00.613508520 I UsageStatsService: User[0] Rollover scheduled @ 2007-11-06 04:19:47(1194322787349)

问题关键在这：AlarmManagerService: Unable to set rtc to 1194236700: No such device
而这个log是在函数static jint android_server_AlarmManagerService_setKernelTime(JNIEnv*, jobject, jlong nativeData, jlong millis)中打印的

213ALOGD("Setting time of day to sec=%d\n", (int) tv.tv_sec); 214 215ret = impl->setTime(&tv); 216 217if(ret < 0) { 218ALOGW("Unable to set rtc to %ld: %s\n", tv.tv_sec, strerror(errno)); 219ret = -1; 220}

而这里的setTime之所以会失败是因为class AlarmImpl 私有成员变量变量rtc_id<0

134if (rtc_id < 0) { 135ALOGV("Not setting RTC because wall clock RTC was not found"); 136errno = ENODEV; 137return -1; 138}

在AlarmManagerService初始化时候调用static jlong android_server_AlarmManagerService_init(JNIEnv*, jobject)设置rtc_id （wall_clock_rtc()）。wall_clock_rtc()中读取rtc设备文件成功和失败的log如下:

01-01 00:22:51.635509509 E AlarmManagerService: found wall clock RTC 0

01-01 00:01:15.384508508 W AlarmManagerService: no wall clock RTC found

242static const char rtc_sysfs[] = "/sys/class/rtc";

269static int wall_clock_rtc() 270{ 271std::unique_ptr dir(opendir(rtc_sysfs), closedir); 272if (!dir.get()) { 273ALOGE("failed to open %s: %s", rtc_sysfs, strerror(errno)); 274return -1; 275} 276 277struct dirent *dirent; 278while (errno = 0, dirent = readdir(dir.get())) { 279unsigned int rtc_id; 280int matched = sscanf(dirent->d_name, "rtc%u", &rtc_id); 281 282if (matched < 0) 283break; 284else if (matched != 1) 285continue; 286 287if (rtc_is_hctosys(rtc_id)) { 288ALOGV("found wall clock RTC %u", rtc_id); 289return rtc_id; 290} 291} 292 293if (errno == 0) 294ALOGW("no wall clock RTC found"); 295else 296ALOGE("failed to enumerate RTCs: %s", strerror(errno)); 297 298return -1; 299}

可以看出这个错误log是由于系统在读取/sys/class/rtc目录下的文件时候没有任何匹配rtc%u的文件。所以问题变成了rtc driver初始化问题，而从boot log中可以看出
snvs_rtc 20cc000.snvs:snvs-rtc-lp: rtc core: registered 20cc000.snvs:snvs-r as rtc0
snvs_rtc 20cc000.snvs:snvs-rtc-lp: setting system clock to 1970-01-01 00:00:12 UTC (12)
rtc driver是有进行初始化，但是否生成相应的设备文件需要在Linux driver里面debug。

----未完待续
【SabreSD-6SX第一次启动Android|SabreSD-6SX第一次启动Android RTC时间无法保存】转载于:https://my.oschina.net/u/3583648/blog/1505375