From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751958AbcFUNfz (ORCPT ); Tue, 21 Jun 2016 09:35:55 -0400 Received: from mx2.suse.de ([195.135.220.15]:55709 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751590AbcFUNfw (ORCPT ); Tue, 21 Jun 2016 09:35:52 -0400 Message-ID: <1466514532.2091.5.camel@suse.com> Subject: Re: [RFC PATCHv2] usb: USB Type-C Connector Class From: Oliver Neukum To: Heikki Krogerus Cc: Guenter Roeck , Andy Shevchenko , Rajaram R , Felipe Balbi , Mathias Nyman , Greg KH , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Date: Tue, 21 Jun 2016 15:08:52 +0200 In-Reply-To: <1463661894-22820-1-git-send-email-heikki.krogerus@linux.intel.com> References: <1463661894-22820-1-git-send-email-heikki.krogerus@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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