From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Subject: Re: should RTS init in serial core be tied to CRTSCTS Date: Thu, 8 Mar 2007 20:40:21 +0000 Message-ID: <20070308204020.GE30023@flint.arm.linux.org.uk> References: <8bd0f97a0703011603m794e00f5x875eb68ad0db05de@mail.gmail.com> <200703080844.32157.rgetz@blackfin.uclinux.org> <20070308134800.GA30023@flint.arm.linux.org.uk> <200703081523.39698.rgetz@blackfin.uclinux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([217.147.92.249]:4569 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933114AbXCHUkj (ORCPT ); Thu, 8 Mar 2007 15:40:39 -0500 Content-Disposition: inline In-Reply-To: <200703081523.39698.rgetz@blackfin.uclinux.org> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Robin Getz Cc: Oleksiy Kebkal , Krzysztof Halasa , Mike Frysinger , Linux Kernel Mailing List , linux-serial@vger.kernel.org On Thu, Mar 08, 2007 at 03:23:39PM -0500, Robin Getz wrote: > On Thu 8 Mar 2007 08:48, Russell King pondered: > > On Thu, Mar 08, 2007 at 08:44:31AM -0500, Robin Getz wrote: > > > That would let you change things are run time, but the problem is at > > > boot time. A default setting needs to be set, so when things initialize, > > > and proc does not exist yet, it is still set properly... > > > > I disagree. "proc does not exist yet" - the only time that applies is > > long before userspace as active. > > Right - We both agree - And setting console=/dev/null in the bootargs still > does not help. Ok, good. > When the kernel initializes the UART Port, it asserts RTS - which confuses > the host it is attached to (in this case, the Linux system is the serial > peripheral). ... which occurs /after/ userspace is up and running, when sysfs is available. So putting it in sysfs is reasonable. > How about adding a module_param to serial core, which the default is to > assert RTS (as is today), and someone (like me) can override with > serial_core.RTS=0 So all ports change behaviour with a single parameter? That'll stop NULL modem cables with hardware flow control enabled working on other ports without compensatory tweaking. No, doing a system-wide change like that is _not_ a solution - it just moves the problem elsewhere. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: