From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751571AbdFENwq (ORCPT ); Mon, 5 Jun 2017 09:52:46 -0400 Received: from mga04.intel.com ([192.55.52.120]:11269 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751557AbdFENwo (ORCPT ); Mon, 5 Jun 2017 09:52:44 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,300,1493708400"; d="scan'208";a="270355066" Date: Mon, 5 Jun 2017 16:52:34 +0300 From: Mika Westerberg To: Lukas Wunner Cc: Greg Kroah-Hartman , Andreas Noever , Michael Jamet , Yehezkel Bernat , Amir Levy , Andy Lutomirski , Mario.Limonciello@dell.com, Jared.Dominguez@dell.com, Andy Shevchenko , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 19/27] thunderbolt: Add new Thunderbolt PCI IDs Message-ID: <20170605135234.GN3454@lahna.fi.intel.com> References: <20170602140524.23367-1-mika.westerberg@linux.intel.com> <20170602140524.23367-20-mika.westerberg@linux.intel.com> <20170605081437.GA7519@wunner.de> <20170605093249.GK3454@lahna.fi.intel.com> <20170605120756.GA7793@wunner.de> <20170605125507.GL3454@lahna.fi.intel.com> <20170605133334.GM3454@lahna.fi.intel.com> <20170605134643.GA7844@wunner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170605134643.GA7844@wunner.de> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 05, 2017 at 03:46:43PM +0200, Lukas Wunner wrote: > On Mon, Jun 05, 2017 at 04:33:34PM +0300, Mika Westerberg wrote: > > On Mon, Jun 05, 2017 at 03:55:07PM +0300, Mika Westerberg wrote: > > > > Yes, it's useful to have ICM-based Thunderbolt on Macs and personally > > > > I'm totally fine with making it the default for Macs which support it. > > > > (I can't speak for Andreas, obviously.) > > > > > > > > However it would be great to give people the *choice* between ICM versus > > > > native mode, for at least two reasons: > > > > > > > > (1) Native mode uses free software. (I assume the ICM firmware remains > > > > closed source.) > > > > > > > > (2) Native mode allows more versatility, e.g. how PCI tunnels are set up > > > > to chained devices: PCI fanout or PCI direct routing, see: > > > > https://developer.apple.com/library/content/documentation/HardwareDrivers/Conceptual/ThunderboltDevGuide/Basics/Basics.html > > > > > > > > Apple supports traffic prioritization to enable audio over Thunderbolt > > > > with higher accuracy / minimal skew, I assume their choice to use > > > > native mode was largely motivated by being able to support specialized > > > > applications like that which are difficult or perhaps impossible to > > > > implement in firmware: > > > > http://pdfpiw.uspto.gov/.piw?Docid=09015384 > > > > > > Right, but do we need to do it now before we have got any feedback from > > > users using Macs with Alpine Ridge and ICM? We can always add the module > > > parameter later if really needed. > > > > It turns out that this is not too big change after all so I think it can > > be included in the ICM patch if you want. > > > > Basically we would have module parameter: > > > > cm=auto|native|icm > > > > where auto is the default. > > > > Does that work? > > Yes, great, thanks! > > And in "auto" mode, it's ICM on non-Macs and TBT3-Macs, and native for > TBT1/TBT2-Macs, right? Yes, that's correct. > Some Falcon Ridge Macs support ICM as well (e.g. the MacBookPro11,4 > and MacBookPro11,5 introduced 2015), but maybe not all of them. > This will have to be tested. If all of them support it, we could > later default to ICM for those as well, or use DMI data to constrain > it to specific models. Unfortunately starting ICM on Falcon Ridge Macs does not work (I tried that already) so there we need to stick with the native implementation.