Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932517AbcKHI4n (ORCPT ); Tue, 8 Nov 2016 03:56:43 -0500 Received: from hqemgate14.nvidia.com ([216.228.121.143]:7543 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932280AbcKHI42 (ORCPT ); Tue, 8 Nov 2016 03:56:28 -0500 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 08 Nov 2016 00:54:26 -0800 Date: Tue, 8 Nov 2016 10:54:20 +0200 From: Peter De Schrijver To: Jon Hunter CC: Thierry Reding , Paul Kocialkowski , , Stephen Warren , , , Alexandre Courbot , Subject: Re: [PATCH] ARM: tegra: nyan: Mark all USB ports as host Message-ID: <20161108085420.GG2478@tbergstrom-lnx.Nvidia.com> References: <20160918102852.6593-1-contact@paulk.fr> <20161107132854.GF12559@ulmo.ba.sec> <13e7ff98-8bc2-ccf7-94bb-4e1d3c61b20d@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <13e7ff98-8bc2-ccf7-94bb-4e1d3c61b20d@nvidia.com> X-NVConfidentiality: public User-Agent: Mutt/1.5.21 (2010-09-15) X-Originating-IP: [10.21.24.170] X-ClientProxiedBy: UKMAIL102.nvidia.com (10.26.138.15) To UKMAIL101.nvidia.com (10.26.138.13) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1468 Lines: 34 On Mon, Nov 07, 2016 at 02:09:31PM +0000, Jon Hunter wrote: > > On 07/11/16 13:28, Thierry Reding wrote: > > * PGP Signed by an unknown key > > > > On Sun, Sep 18, 2016 at 12:28:52PM +0200, Paul Kocialkowski wrote: > >> Nyan boards only have host USB ports (2 external, 1 internal), there is > >> no OTG-enabled connector. > >> > >> Signed-off-by: Paul Kocialkowski > >> --- > >> arch/arm/boot/dts/tegra124-nyan.dtsi | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > > > > Where is this information coming from? I don't have one of the Nyans > > myself, but one of the Tegra132 devices I have, which I think was > > derived from one of the Nyans uses one of the external host ports as > > forced recovery port, for which it would need OTG. > > > > I suspect that the way to get U-Boot onto the Nyans is via tegrarcm? > > In that case I think one of the ports must be OTG. > > It is true that the port on the back on the nyan-big can be used with > recovery mode. I was thinking that this is not a true OTG port as it is > just a 4-pin type A socket and does not have an ID pin. Thinking some > more about this the USB spec does include a "Host Negotiation Protocol > (HNP)" that allows a host and device to swap roles and so keeping it as > OTG seems valid afterall. I don't think the bootrom implements that though. I expect recovery mode to just program the controller in device mode, without performing any negotiation. Peter.