I've seen various reports of iPhone 6 Plus get 2.1A charging from Macbook Pro.
http://blog.equinux.com/2014/09/iphone-6-and-6-plus-charging-secrets-revealed
http://9to5mac.com/2011/03/25/new-macbook-pros-get-serious-ipad-charging-juice-in-their-usb-ports/
However, I'm unable to replicated that on my own Macbook Pro Retina 15" 2015.
It stays at 1A as below
Current Available (mA): 500
Current Required (mA): 500
Extra Operating Current (mA): 500
Currently on Yosemite and plugged in.
Anyone having the same issue (or has been able to get the Macbook to power out 2.1A?)
Best Answer
I have the same 2015 15" MBP, just upgraded to OS 10.13.4, and with my iPhone 6S+ discharged to 13%, I got:
BUT, I only get that in the right USB port. When I plug it into the left USB port at 13% charge, it Beeps once a second, so I removed it. Once the phone is charged to 20%, it will charge in either port. The phone is now charged to 98%, but the refreshed System Info still shows the same values.