Power Brick control

[jcdutton]

Hi,

The FW USB-C PD is a "dual" mode device, in that it can both source and sink power. This works quite well when one plugs in a "source" mode device or a "sink" mode device. There is no ambiguity there. The problem comes when one has a Power Brick that is also a "dual" mode device.

dual mode device <=> dual mode device Who wins, who charges who?

I would like to add an ectool command so that a user can hint to a particular USB port whether it should act as a source or a sink when it sees a dual mode device. It allows the user to override unexpected behavior.

I am happy to edit the EC source code myself to implement this feature. My question is, what command does the EC need to send the USB-C port to change it from being a "dual" mode device to be a "sink" mode only device?

[brlin-tw]

Not sure, but I think there's a sysfs thing on Linux that can do this exact thing.