From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932271AbcFBGfA (ORCPT ); Thu, 2 Jun 2016 02:35:00 -0400 Received: from mx2.suse.de ([195.135.220.15]:45790 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751529AbcFBGeq (ORCPT ); Thu, 2 Jun 2016 02:34:46 -0400 Message-ID: <1464849057.8527.5.camel@suse.com> Subject: Re: [RFC PATCHv2] usb: USB Type-C Connector Class From: Oliver Neukum To: Guenter Roeck Cc: Andy Shevchenko , Rajaram R , Felipe Balbi , Heikki Krogerus , Mathias Nyman , Greg KH , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Date: Thu, 02 Jun 2016 08:30:57 +0200 In-Reply-To: <20160601232926.GA8463@roeck-us.net> References: <1463661894-22820-1-git-send-email-heikki.krogerus@linux.intel.com> <1464773169.4051.8.camel@suse.com> <20160601232926.GA8463@roeck-us.net> 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 Wed, 2016-06-01 at 16:29 -0700, Guenter Roeck wrote: > On Wed, Jun 01, 2016 at 11:26:09AM +0200, Oliver Neukum wrote: > > On Thu, 2016-05-19 at 15:44 +0300, Heikki Krogerus wrote: > > > Just noticed that the "active" file is for now read only, but it needs > > > to be changed to writable. That file will of course provide means for > > > the userspace to Exit and Enter modes. But please note that the > > > responsibility of the dependencies between the modes, say, if a plug > > > needs to be in one mode or the other in order for the partner to enter > > > some specific mode, will fall on the Alternate Mode specific drivers > > > once we have the altmode bus. I remember there were concerns about > > > this in the original thread. > > > > There's one thing we haven't touched upon yet. And I cannot really find > > an answer in the spec. > > > > What do we do if we return from S4 or S3? I think we need to restore > > the ALternate Mode because our display may be running over that > > Alternate Mode. > > If we want to support USB persist we also need to restore data role > > after S4. > > > I don't have an answer ... but another interesting question. > > How do we distinguish between alternate modes supported by a host vs. > alternate modes supported by a sink ? typec_capability includes a pointer > to alternate modes supportedf by the connector, but it is not clear if > those are alternate modes supported as host, or alternate modes supported > as device, or alternate modes supported by both. I was under the impression that this applies to the current role. > This doesn't matter much if only a fixed role is supported, but it does matter > for dual role ports. A laptop will typically only support DisplayPort as host, > for example. > > Any idea ? I would state the obvious that we need separate directories for that. And how do we express captive cables? Regards Oliver