iPad 10.5 not charging connected to macbook pro

[anonymous4a]

I have a macbook pro retina 2012, when I try to charge my iPad through the right side usb port it says, "not charging". But the left side usb port can charge it . Why can't my iPad charge through the right usb port ?

 

[kazmac]

Some ports on older macs may not recognize newer iDevices, or more importantly have the power to charge the iDevice through a specific port.

This discussion at the official Apple support forum mentions the issue:

https://discussions.apple.com/thread/4882179?tstart=0

Here's the Apple support document:

https://support.apple.com/en-us/HT201569