Say Y here to enable external connector class (extcon) support.
This allows monitoring external connectors by userspace
via sysfs and uevent and supports external connectors with
multiple states; i.e., an extcon that may have multiple
cables attached. For example, an external connector of a device
may be used to connect an HDMI cable and a AC adaptor, and to
host USB ports. Many of 30-pin connectors including PDMI are
also good examples.

source code:

drivers/extcon/