From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753758Ab0CXUyP (ORCPT ); Wed, 24 Mar 2010 16:54:15 -0400 Received: from senator.holtmann.net ([87.106.208.187]:54924 "EHLO mail.holtmann.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752027Ab0CXUyN (ORCPT ); Wed, 24 Mar 2010 16:54:13 -0400 Subject: Re: [PATCH 4/6] drivers:misc: sources for Init manager module From: Marcel Holtmann To: Pavan Savoy Cc: Alan Cox , Greg KH , PavanSavoy , "linux-kernel@vger.kernel.org" In-Reply-To: <538832.38767.qm@web94915.mail.in2.yahoo.com> References: <538832.38767.qm@web94915.mail.in2.yahoo.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 24 Mar 2010 13:54:04 -0700 Message-ID: <1269464044.11714.135.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 (2.28.3-1.fc12) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pavan, > > > Which puts me back to square 1, > > the requirement is TTY device should be open, only when > > either BT, FM or GPS would want to use it. > > > [with your patch one of the steps of installing ldisc > > would be reduced upon opening]. > > > > Perhaps but its up to you how you write your low level > > driver and how the > > ldisc indicates it wishes to be active (eg speed B0 is used > > to indicate > > 'no carrier' in many cases) > > > > > Actually why do I even need a TTY device in this case > > - right ? > > > ldisc driver can do the tty->ops->write and > > tty_read and put it up on different interfaces like > > eth0/hci0 or /dev/radio0 etc.. > > > > You don't need a tty if you are simply demuxing some kind > > of stream of > > bytes to/from the hardware and you gain nothing from the > > tty layer and > > user space interfaces such as control signal and speed > > setting. > > > > I still want to maintain this as a ldisc driver and the TTY layer is still required to be able to use this with different sort of serial drivers. > > example: > We do a have a system here where both 8250/omap-serial co-exist creating their own device nodes (ttyS for 8250, ttyO for omap-serial) and I would want to be able to on boot suggest which serial driver to use, so I can open/install ldisc on ttyS or on ttyO. > > > > That may be even cleaner in your case as you can then then > > provide > > suitable links between your demux and the drivers attached > > to it > > indicating when they should be on or off. > > And as Marcel suggested, can't really put in the PM/UART-clk shut off code in ldisc driver because few of these driver provide interfaces and few don't. > > So is there no way this can be accepted with the sysfs entry way of communication ? to be quite honest, I can't see how that can be accepted right now. It looks wrong on too many levels. Regards Marcel