From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 71FFC884 for ; Wed, 5 Aug 2015 09:12:00 +0000 (UTC) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id F16FE130 for ; Wed, 5 Aug 2015 09:11:59 +0000 (UTC) Date: Wed, 5 Aug 2015 11:11:56 +0200 From: Samuel Ortiz To: Linus Walleij Message-ID: <20150805091156.GB27438@zurbaran.home> References: <20150723084251.54da2be0@gandalf.local.home> <20150723154014.GD11162@sirena.org.uk> <55B7FD82.8010806@sonymobile.com> <20150728230743.GO4753@usrtlx11787.corpusers.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Cc: Bjorn Andersson , "ksummit-discuss@lists.linuxfoundation.org" , "riverful.kim@samsung.com" , "kyungmin.park@samsung.com" , John Stultz , Pavel Machek , Greg KH Subject: Re: [Ksummit-discuss] [CORE TOPIC] Mainline kernel on a cellphone List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Aug 05, 2015 at 10:46:19AM +0200, Linus Walleij wrote: > On Wed, Aug 5, 2015 at 10:40 AM, Linus Walleij wrote: > > On Tue, Aug 4, 2015 at 12:36 AM, Marcel Holtmann wrote: > (...) > >> In a perfect world I would prefer we are not using the Bluetooth HCI line discipline > >> at all. The problem right now is that everybody wants to enable the UART as > >> /dev/ttyFOO and then move on. However in reality they are not general purpose > >> TTY devices. The only thing you can ever do with them is tell the Bluetooth > >> subsystem that there is a TTY device and attach its line discipline to it. > > > > This is done from userspace right? I never managed to wrap my head around > > this because it seemed so odd and plainly hackish. > > > > In this ST-Ericsson driver for CG2900: > > http://marc.info/?l=linux-kernel&m=134873373526049&w=2 > > the HCI link is used to tunnel things that are not Bluetooth, also > > GPS and FM radio is controlled over HCI. Yeah sorry, I didn't invent > > it... the HCI is then run over a UART. > > Damned I snapped off the latter part of your message. Typing and > mailing to quickly. This was obviously in response to: > > >> Or and did I mention that some manufactures actually put FM radio and GPS > >> controls behind the Bluetooth chip. So access to these slave devices goes > >> via the Bluetooth HCI. This means that you have this fun dependency: > >> > >> FM radio -> Bluetooth HCI -> UART -> UART slave > > So what I wanted to ask is who else is doing this apart from > CG2900/STLC2690? Is it a common pattern? Unfortunately it seems to be a common pattern. TI combos used to do that at well. Cheers, Samuel.