I would like to point out that your fix also effectively removes the phones ability to remove background noise since it removes the secondary microphone's function. Not sure if this was intended or this is the fix you described since as far as I know the call echo issue is not caused by the secondary microphone but rather it is a dialer issue.
To users of my cyanogenmod rom: don't use this, it removes a lot of the tweaks I made. If you want to use this, wait until I make a version with this patch.
Also I think the install instructions should be clearer, because if the permissions aren't set correctly, you end up with a bootloop. Permissions should be rw-r--r-- (0644).
One more thing: did you create this? If not this shouldn't be in development.
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