不少 Nexus 5 用家都发现当手机使用相机相关的 Apps (尤其是 Skype) 时，CPU 用量都会明显持续提升了不少，都是来自一个 mm-qcamera-daemon process，在电池用量中就会见到 mm-qcamera-daemon 占了最大比重。在 Android Issue Tracker，已有数百人标记了这个 Issue (#60058)。
Google Project Member 昨晚终于回应了这个 Bug，表示已经修复了有关问题，并会在下一个更新推出有关的修正。不过就未知何时推出，因应仍要进行相关的测试。
We believe we have fixes for the current high CPU reports on N5 due to mm-qcamera-daemon, and they will be included in the next maintenance update.
这位 Project Member 表示，这个 Bug 是沿于相机相关的程序，由于一般相机 Apps 只会在运行时才存取相机功能，所以只会在运行相机 Apps 时才会引发个 Bug 出现。不过最近 Skype 推出了更新，会在背景程序存取相机功能，因而引致这个 Bug 不断被 Trigger，所以这个问题近期出现得更加频密 (Skype 本身是没有问题的)。
More recently, there’s been a significant increase in the frequency of reported problems. These may be related to a recent update to Skype, which seems to access the camera regularly from its background service in some way that triggers this bug (note, we don’t currently believe there’s a bug in Skype itself).
暂时靠 Reboot 解决
在修正未推出之前，要解决 “mm-qcamera-daemon 高 CPU 用量” 问题只有将手机重新启动才可。
Until then, rebooting the phone is the only way to stop the high CPU usage/lack of camera function once it starts.
Source: Android Open Source Project Issue Tracker