RPi2 USB power: is there a conclusive answer?

[Nachteule]

There is only one answer:

External non-powered HDD's and CD-ROM's are usually working beyond the USB2.0 limits (which only allows 500mA). So, connecting such a device may work, or not. You always have to try it

usb_max_current=1 doubles the current which can be delivered to the USB ports. So if the power supply is good enough and the current consumption is hot higher than the current allowed by the onboard fuse, again, it may work or not.

The 2mA value is the maximum current the USB device will consume from the USB port and has nothing to do with the power supply or the max current which can be delivered by the USB port

In my case (a WLAN and a DVB-C stick is connected) I get

Terminal

Bus 002 Device 002: ID 0cf3:7015 Atheros Communications, Inc. TP-Link TL-WN821N v3 802.11n [Atheros AR7010+AR9287]
MaxPower 500mA
Bus 001 Device 003: ID 0ccd:008e TerraTec Electronic GmbH Cinergy HTC XS
MaxPower 500mA

both devices reports max current of 500mA. But, if I connect one of these devices without parameter usb_max_current=1
to the RPi2, it won't work.