Re: [RFC PATCHv2] usb: USB Type-C Connector Class

From: Oliver Neukum
Date: Tue Jun 21 2016 - 09:36:48 EST


On Thu, 2016-05-19 at 15:44 +0300, Heikki Krogerus wrote:
> The purpose of this class is to provide unified interface for user
> space to get the status and basic information about USB Type-C
> Connectors in the system, control data role swapping, and when USB PD
> is available, also power role swapping and Alternate Modes.

This raises two more questions.

1. Booting

It is possible that our only display and, worse, our source
of power is a display that can be used only in an alternate mode
and is connected via a type C connector.

We need some kind of boot time support for alternate modes.

The firmware will surely want to display something. So it is possible
that we start the OS will a valid power contract. How do we deal
with that? Renegotiate?

2. Multiple GPUs

How do we know which GPU is connected to which port?

Regards
Oliver