From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 30 Jul 2002 11:50:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 30 Jul 2002 11:50:33 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:59410 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id ; Tue, 30 Jul 2002 11:50:32 -0400 Date: Tue, 30 Jul 2002 16:53:51 +0100 From: Russell King To: Stuart MacDonald Cc: Matthew Wilcox , greg@kroah.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.linuxppc.org Subject: Re: [parisc-linux] 3 Serial issues up for discussion (was: Re: Serial core problems on embedded PPC) Message-ID: <20020730165351.C7677@flint.arm.linux.org.uk> References: <20020729040824.GA2351@zax> <20020729100009.A23843@flint.arm.linux.org.uk> <20020729144408.GA11206@opus.bloom.county> <20020729181702.E25451@flint.arm.linux.org.uk> <20020729231927.D3317@parcelfarce.linux.theplanet.co.uk> <008801c237d6$8b7dc640$294b82ce@connecttech.com> <20020730161940.P1441@parcelfarce.linux.theplanet.co.uk> <00f801c237df$d09d4e40$294b82ce@connecttech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <00f801c237df$d09d4e40$294b82ce@connecttech.com>; from stuartm@connecttech.com on Tue, Jul 30, 2002 at 11:43:13AM -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 30, 2002 at 11:43:13AM -0400, Stuart MacDonald wrote: > No, I was wondering if leaving the USB serial major 18[89] alone would > be a better idea. Since posting, I've been thinking that the usb > serial driver presents the same interface to the tty layer as any > other serial device so I guess it's not a bad idea. To be able to suck in USB (and some of the other drivers), two changes need to be made to the core: 1. the change_speed method needs to be handled differently; we currently assume a UART-style implementation here. We need to change this around before 2.6 anyway for ports which don't support all the termios settings (SuSv3 requires that any unimplemented features retain their original values, so for example if we don't have RTS and CTS lines on a particular implementation, CRTSCTS should be initially off and not turn on-able.) 2. USB devices want "packets" of data to write rather than the ring- buffer we currently use for UARTs. (time to start ebaying for USB serial devices...) -- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html