Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754322AbdCNBSU (ORCPT ); Mon, 13 Mar 2017 21:18:20 -0400 Received: from hera.aquilenet.fr ([141.255.128.1]:41533 "EHLO hera.aquilenet.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752206AbdCNBST (ORCPT ); Mon, 13 Mar 2017 21:18:19 -0400 Date: Tue, 14 Mar 2017 02:18:14 +0100 From: Samuel Thibault To: Greg Kroah-Hartman , okash.khawaja@gmail.com, Jiri Slaby , linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, linux-serial@vger.kernel.org, Rob Herring , Kirk Reiser , Chris Brannon , speakup@linux-speakup.org Subject: Re: [patch 0/7] staging: speakup: introduce tty-based comms Message-ID: <20170314011814.p3t4zfcx3cxhgvwl@var.youpi.perso.aquilenet.fr> Mail-Followup-To: Samuel Thibault , Greg Kroah-Hartman , okash.khawaja@gmail.com, Jiri Slaby , linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, linux-serial@vger.kernel.org, Rob Herring , Kirk Reiser , Chris Brannon , speakup@linux-speakup.org References: <20170313220551.312820470@gmail.com> <20170313221404.GA22871@kroah.com> <20170314004701.kuecu2zu4md5ccrq@var.youpi.perso.aquilenet.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170314004701.kuecu2zu4md5ccrq@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: 2133 Lines: 46 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? > > 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 :) The issue that remains is the "tty" part: we'd need there the tty_port, the parent device, the tty driver, the idx. All we know when we load speakup is "ttyS0". That's where going through the cdev to attach a line discipline was simpler :) Samuel