From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1381524204.5630.91.camel@pasglop> Subject: Re: [PATCH 1/2] tty/hvc_console: Add DTR/RTS callback to handle HUPCL control From: Benjamin Herrenschmidt Date: Sat, 12 Oct 2013 07:43:24 +1100 In-Reply-To: <20131011124707.GA6082@linux.vnet.ibm.com> References: <1372777635-10423-1-git-send-email-brueckner@linux.vnet.ibm.com> <1372777635-10423-2-git-send-email-brueckner@linux.vnet.ibm.com> <1381475711.5630.67.camel@pasglop> <20131011124707.GA6082@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Archive: To: Hendrik Brueckner Cc: linux-s390@vger.kernel.org, gregkh@linuxfoundation.org, heiko.carstens@de.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, brueckner@linux.vnet.com, schwidefsky@de.ibm.com, jslaby@suse.cz List-ID: On Fri, 2013-10-11 at 14:47 +0200, Hendrik Brueckner wrote: > The tiocmget/tiocmset callbacks are used to set and get modem status and > triggered through an tty ioctl. > > The dtr_rts() callback is different and it is used for DTS/RTS handshaking > between the hvc_console (or any other tty_port) and the tty layer. The tty > port layer uses this callback to signal the hvc_console whether to raise or > lower the DTR/RTS lines. This is different than the ioctl interface to > controls the modem status. Well, DTR at least is the same via both callbacks... Also normal handshaking is normally RTS/CTS, only some HW setups "hijacks" DTR for RTS (old Macs come to mind). Cheers, Ben. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757242Ab3JKUn5 (ORCPT ); Fri, 11 Oct 2013 16:43:57 -0400 Received: from gate.crashing.org ([63.228.1.57]:59608 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755682Ab3JKUnw (ORCPT ); Fri, 11 Oct 2013 16:43:52 -0400 Message-ID: <1381524204.5630.91.camel@pasglop> Subject: Re: [PATCH 1/2] tty/hvc_console: Add DTR/RTS callback to handle HUPCL control From: Benjamin Herrenschmidt To: Hendrik Brueckner Cc: jslaby@suse.cz, gregkh@linuxfoundation.org, brueckner@linux.vnet.com, heiko.carstens@de.ibm.com, schwidefsky@de.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Date: Sat, 12 Oct 2013 07:43:24 +1100 In-Reply-To: <20131011124707.GA6082@linux.vnet.ibm.com> References: <1372777635-10423-1-git-send-email-brueckner@linux.vnet.ibm.com> <1372777635-10423-2-git-send-email-brueckner@linux.vnet.ibm.com> <1381475711.5630.67.camel@pasglop> <20131011124707.GA6082@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2013-10-11 at 14:47 +0200, Hendrik Brueckner wrote: > The tiocmget/tiocmset callbacks are used to set and get modem status and > triggered through an tty ioctl. > > The dtr_rts() callback is different and it is used for DTS/RTS handshaking > between the hvc_console (or any other tty_port) and the tty layer. The tty > port layer uses this callback to signal the hvc_console whether to raise or > lower the DTR/RTS lines. This is different than the ioctl interface to > controls the modem status. Well, DTR at least is the same via both callbacks... Also normal handshaking is normally RTS/CTS, only some HW setups "hijacks" DTR for RTS (old Macs come to mind). Cheers, Ben.