N4 wifi Qualcomm driver Bug, 螢幕關閉時wifi對ARP沒有響應,大部分會在螢幕關閉15分鐘後才會有影響....其他請閱讀原文.
自己使用 N4,也沒感覺到有太大問題,為了心安,照XDA上修改一下/system/etc/wifi/WCNSS_qcom_cfg.ini
原文 http://forum.xda-developers.com/showthread.php?t=2072930
One issue that has yet to be fixed as of 4.2.2 is the ability for the phone to respond to ARP requests while the screen is off. This results in the phone being unable to receive network traffic over wifi under certain circumstances while asleep. The most noticeable effect of this issue is notifications being delayed for up to 15 minutes while the screen is off. During this time, turning the screen on will result in these delayed notifications flooding in all at once. You may also notice the wifi signal indicator turning gray immediately after turning the screen on followed a few seconds later by it turning blue. Another symptom that some have had is incoming VoIP calls not ringing the phone while the screen is off but working fine while the screen is on.
This issue has been confirmed by Google (https://code.google.com/p/android/is...etail?id=42272) and is related to a buggy implementation of ARP Offload in the Nexus 4 wifi driver.
http://forum.xda-developers.com/showthread.php?t=2072930
Disable filtering on the N4
Another solution is to disable the unicast and/or multicast filtering on your N4 by modifying an ini file on the phone. This will allow the phone to see all broadcast traffic (including ARP) during sleep. As a result the phone will be able to properly respond to ARP requests.
The positive is once you make this change, the phone will properly respond to ARP requests without having to make any other changes. It will work with any wifi network that you connect to.
The negative is making this change will cause a negative impact on battery life. How much of an impact depends entirely on how much broadcast and multicast traffic exists on your network. The more traffic, the more the phone is woken up, the more the battery hit will be. The only way to know how much of a battery impact you will have is to test it out.
To make the ini file change manually (see below for installable zip files):
Make sure your phone is rooted
Remount /system as RW
Make a backup of file /system/etc/wifi/WCNSS_qcom_cfg.ini
Edit the file /system/etc/wifi/WCNSS_qcom_cfg.ini
Change the line "McastBcastFilter=3" to "McastBcastFilter=0"
Save the file and double check file permissions (-rw-r--r-- root root)
Reboot the phone
從 APP 打開
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