Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933577AbdCVAFb (ORCPT ); Tue, 21 Mar 2017 20:05:31 -0400 Received: from hera.aquilenet.fr ([141.255.128.1]:59683 "EHLO hera.aquilenet.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756924AbdCVAF3 (ORCPT ); Tue, 21 Mar 2017 20:05:29 -0400 Date: Wed, 22 Mar 2017 01:05:24 +0100 From: Samuel Thibault To: Rob Herring , Greg Kroah-Hartman , okash.khawaja@gmail.com, Jiri Slaby , "linux-kernel@vger.kernel.org" , devel@driverdev.osuosl.org, "linux-serial@vger.kernel.org" , Kirk Reiser , Chris Brannon , speakup@linux-speakup.org Subject: Re: [patch 0/7] staging: speakup: introduce tty-based comms Message-ID: <20170322000524.7k653z7ui2zzgan6@var.youpi.perso.aquilenet.fr> Mail-Followup-To: Samuel Thibault , Rob Herring , Greg Kroah-Hartman , okash.khawaja@gmail.com, Jiri Slaby , "linux-kernel@vger.kernel.org" , devel@driverdev.osuosl.org, "linux-serial@vger.kernel.org" , Kirk Reiser , Chris Brannon , speakup@linux-speakup.org References: <20170313220551.312820470@gmail.com> <20170313221404.GA22871@kroah.com> <20170314004701.kuecu2zu4md5ccrq@var.youpi.perso.aquilenet.fr> <20170314011814.p3t4zfcx3cxhgvwl@var.youpi.perso.aquilenet.fr> <20170315150323.pjda5qnxauxk5pcf@var.youpi.perso.aquilenet.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170315150323.pjda5qnxauxk5pcf@var.youpi.perso.aquilenet.fr> Organization: I am not organized User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3136 Lines: 65 Hello, So Rob, how do you see this going? Shall we introduce a serdev_device *tty_port_register_serdev_device(tty, device)? Will you work on it or should I give it a try? Samuel Samuel Thibault, on mer. 15 mars 2017 16:03:23 +0100, wrote: > Rob Herring, on mer. 15 mars 2017 09:45:59 -0500, wrote: > > On Mon, Mar 13, 2017 at 8:18 PM, Samuel Thibault > > wrote: > > > Samuel Thibault, on mar. 14 mars 2017 01:47:01 +0100, wrote: > > >> Greg KH, on mar. 14 mars 2017 06:14:04 +0800, wrote: > > >> > On Mon, Mar 13, 2017 at 10:05:51PM +0000, okash.khawaja@gmail.com wrote: > > >> > > This patchset introduces a TTY-based way for the synths to communicate > > >> > > with devices as an alternate for direct serial comms used by the synths > > >> > > at the moment. It then migrates some of the synths to the TTY-based > > >> > > comms. Synths migrated in this patchset are dummy, acntsa, bns and > > >> > > txprt. > > >> > > > >> > What about using the serbus code that is now in the tree? That should > > >> > make this a lot easier than your patchset from what I can see. > > >> > > >> Mmm... AIUI from reading tty_port_register_device_attr, one > > >> would have to have registered a speakup serdev device driver > > >> *before* tty_port_register_device_attr gets called, so that > > >> serdev_tty_port_register matches the driver in the loop of > > >> of_serdev_register_devices, and no TTY cdev is created? > > > > Not exactly. The driver doesn't have to be registered nor loaded, but > > the device does have to be present so no tty cdev is created. The only > > way a device is present currently is when a node is in the DT. I > > expect the x86 folks will be adding ACPI support soon. > > Ok, but in our case there is no hardware device that the system can > see/probe, it's just plugged externally. > > > >> That would mean that speakup can not be loaded as a module after ttyS0 > > >> initialization, that won't fly for our use needs. The line discipline > > >> mechanism allows us to attach ourself to an existing tty. Could we > > >> imagine a tty_port function which removes the cdev and tries to register > > >> the tty port again to serdev? > > >> > > >> What we basically need to be able to say on speakup module load is > > >> e.g. "I'm now attaching a device to ttyS0, use this serdev_device_ops to > > >> discuss with it". > > > > > > That for_each_available_child_of_node loop is really way more complex > > > than what we need. And what's more, it's not working without CONFIG_OF > > > (!) > > > > > > It would really make sense to me to have a > > > > > > serdev_device *tty_port_register_serdev_device(tty, device) > > > > > > which unregisters the character device of the tty, and creates instead a > > > controler with the given device plugged to it. Really much like a line > > > discipline, but way simpler :) > > > > What would trigger calling this function? > > From the user point of view, loading the speakup module for the external > device, typically, with "ttyS0" as module parameter. Then the speakup > init function can do whatever it needs to achieve this :)