iPhone 6S Plus - Macbook Pro USB Charging not reaching 2.1A 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://www.iphonehacks.com/2014/09/iphone-6-iphone-6-plus-can-charged-faster-ipad-charging-adapter.html

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?)
I have the same 2015 15" MBP, just upgraded to OS 10.13.4, and with my iPhone 6S+ discharged to 13%, I got: 


Current Available (mA): 500
Current Required (mA): 500
Extra Operating Current (mA): 1600
Sleep Current (mA): 2100


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.