How to set Android M default USB config to MTP rather than "charging only"?

Question

Whenever my device (Nexus 5, Android M Preview 3) connects via USB, the USB config always defaults to "charging only".

This is quite problematic because the USB port on my device is faulty and sometimes disconnects and reconnects when bumped and so I have to manually change the mode to MTP (media transfer protocol) from the notification drawer each time.

• Debugging mode is enabled
• Develop settings -> USB Configuration is set to MTP.

Answer 1

I just tried this on my Nexus 5 (Android 6.0.1) and it worked:

• Make sure your phone is NOT connected to any device over USB cable
• Go to Settings - Developer options - Select USB Configuration
• Set your desired default connection type

The trick was to have a phone disconnected from USB. I guess the idea behind such a behavior was that if you set an USB connection type while your phone is not connected to any device, it will be treated as a default behavior.

Answer 2

By Default, Android 6.0 does not provide an automated method to select MTP when the device is connected as USB. After much wait and research through XDA, blogs, stackoverflow etc, the best solution I found to this was a small application, named MTP enabler PRO Marshmallow(4.5 MB) - built by one of the users to overcome this problem.

This requires a rooted device.

Below is a link to download the APK file.

http://forum.xda-developers.com/android/apps-games/app-mtp-enbaler-t3263467

Below is a link to the app in PlayStore(paid app)

https://play.google.com/store/apps/details?id=mtp_enabler.esolutions4you.de.mtpenabler&hl=en

Hope it helped.