When I connect an Android 6 phone with my pc via USB, it always connects as "USB for charging". I have to set it to "connect as camera" (PTP) manually (for ADB to work) every time.
Can I set a default option somewhere and haven't found it yet?
While there may be a hack around somewhere (I don't have Android M yet), Google, in the changelog of Android 6.0 has noted:
Device connections through the USB port are now set to charge-only mode by default. To access the device and its content over a USB connection, users must explicitly grant permission for such interactions.
Well, the answer is no for now, officially, that is.