From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1525762915; cv=none; d=google.com; s=arc-20160816; b=UYxThLzoN/bJ5JSFdKEAww+rJdll6+7jT29rxSjtQhCRWOaWbH3+rUoFZVreAp4/r+ ZNH77EJkC+KBXAXkXTnM7dgbsFAFKIszyQ2frQ99HA5avV5geB0HZrs7bvkm5xzlhZXb GoTXLewm6rvs18s64qGUJrSOpVKmjfjnQDZ1wywcUQisRgjOh7vAMOJQqFoZpS7P5tmL Y6OHhpkVUpFfyMtEQD1c+W1w8FudbTOJpNEAa3ykb2/qU0aHDI58Q4BKNFvGh6ZIVjdR HVu0E5w3a5D4mNxA6txZa6Mxkl2Qsk4P8jVyavYb6dHS2S0H+d8NuehSi1u/tekYWFU8 Kdeg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:sender:dkim-signature :arc-authentication-results; bh=bJt3phMwrsYIcJVwRbjY2LWJVfYJ1hQBoPXk6u9hvYU=; b=1HG8U3gwzaQ9MCD8B0pSDl25a3NLnEIpbe4qJ5fimg3HEtqHwtKFG3MKg6zZAQBoSn 8grFljMsY2A05HqzEFO1KQXm8h+CRlUn4iE71ktBjM5IM+anHjAIPiu6C+CUVPuKtMdn tBd/8bnm+IP6lXzen9aQMxwz2s2yATODRUGbI995vFrG/rJYjqaRxOa7MqRuZeBMEFps FDhM6DaAqRZdjvVirfGahNlpB6aLivmszyckZatsQLNyGvQlwG/u3+DI92e6w7aPZPET JJMa7Y2X8kP975hXNqd0nlh+Imr8be2DlVtI5chOFTksDDs8ylUdhNwLLfk7SNYBJ6P+ v9Pg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=G+Xl1BuH; spf=pass (google.com: domain of jhovold@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=jhovold@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=G+Xl1BuH; spf=pass (google.com: domain of jhovold@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=jhovold@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Google-Smtp-Source: AB8JxZqk2wUqy7MthEmek4CMzkV4859/n+wlV6Z/rnF6A7bR/ERHB9by07iSziWeZnKDQk81AcP/3w== Sender: Johan Hovold Date: Tue, 8 May 2018 09:01:53 +0200 From: Johan Hovold To: Marcel Holtmann Cc: Johan Hovold , Sebastian Reichel , Greg Kroah-Hartman , Rob Herring , Mark Rutland , Andreas Kemnade , Arnd Bergmann , "H . Nikolaus Schaller" , Pavel Machek , LKML , devicetree@vger.kernel.org Subject: Re: [PATCH 0/7] gnss: add new GNSS subsystem Message-ID: <20180508070153.GX2285@localhost> References: <20180424163458.11947-1-johan@kernel.org> <20180504132741.brn5jqv5ufjhp7ky@earth.universe> <20180507102056.GU2285@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.5 (2018-04-13) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1598647061282688193?= X-GMAIL-MSGID: =?utf-8?q?1599878374329366978?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Mon, May 07, 2018 at 09:06:44PM +0200, Marcel Holtmann wrote: > >> I have one concern, though. While providing raw data by > >> default is fine generally, it is a problem with device > >> auto-discovery. I think there should be some IOCTL from > >> the start, that can be used to inform userspace about > >> the raw protocol being used (i.e. "NMEA"). I fear, that > >> userspace may start to just assume raw = NMEA without > >> having this (especially since all initial drivers provide > >> NMEA). > > > > One problem I see here would be that the driver does not necessarily > > know either what protocol is currently being used. Some devices have > > boot-pins which can be used to configure the initial protocol used (and > > this could perhaps be reflected in DT), but this can often later be > > changed (by user space) and even be made persistent using battery-backed > > ram or eeproms. > > > > Also note that at least u-blox devices supports having more than one > > protocol active on the same port... > > as long as userspace can determine that it is GNSS hardware and what > hardware it is, then you deal with the rest in userspace. Yeah, I think that will do for now. Thanks, Johan