From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761352Ab3JPXV3 (ORCPT ); Wed, 16 Oct 2013 19:21:29 -0400 Received: from e23smtp02.au.ibm.com ([202.81.31.144]:53110 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755729Ab3JPXV1 (ORCPT ); Wed, 16 Oct 2013 19:21:27 -0400 Message-ID: <1381965672.17841.71.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: Wed, 16 Oct 2013 18:21:12 -0500 In-Reply-To: <20131016090432.GA6053@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> <1381524204.5630.91.camel@pasglop> <20131015153626.GA6129@linux.vnet.ibm.com> <1381870070.17841.24.camel@pasglop> <20131016090432.GA6053@linux.vnet.ibm.com> Organization: IBM Australia Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13101623-5490-0000-0000-00000455102F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2013-10-16 at 11:04 +0200, Hendrik Brueckner wrote: > Indeed, two callbacks change the DTR line. The main difference is that > tiocmget/tiocmset can be called from user space by ioctl. That's not the case > for the dtr_cts callback. Also, tiocmget/tiocmset provide more flags that can > be changed (ST, SR, CTS, CD, RNG, RI, ...) > > Assume we would like to unify them have a single callback to change DTR, then > we have to take care of these differences. So the question to you now is > whether you plan for a) other modem flags to be changed and b) if changing the > DTR line (or other control flags) through an ioctl? > > Depending on your results, I could work on sth that helps us both and reduces > the callbacks. Can we not just have the users of dtr_cts just call the backend's tiocmset ? If they need to filter or clamp bits, we could handle all that in hvc_console by caching the user intended value and passing a cooked value down to the backend.. None of that is urgent or anything, it's just odd and would be nice to cleanup. Cheers, Ben.