From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e06smtp13.uk.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id B48F92C00BC for ; Thu, 17 Oct 2013 19:16:54 +1100 (EST) Received: from /spool/local by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 17 Oct 2013 09:16:49 +0100 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id DFD57219005F for ; Thu, 17 Oct 2013 09:16:45 +0100 (BST) Received: from d06av12.portsmouth.uk.ibm.com (d06av12.portsmouth.uk.ibm.com [9.149.37.247]) by b06cxnps3074.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r9H8GX0x14090330 for ; Thu, 17 Oct 2013 08:16:33 GMT Received: from d06av12.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av12.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r9H8Ghu6015631 for ; Thu, 17 Oct 2013 02:16:45 -0600 Date: Thu, 17 Oct 2013 10:16:42 +0200 From: Hendrik Brueckner To: Benjamin Herrenschmidt Subject: Re: [PATCH 1/2] tty/hvc_console: Add DTR/RTS callback to handle HUPCL control Message-ID: <20131017081642.GA6134@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> <1381965672.17841.71.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1381965672.17841.71.camel@pasglop> Cc: linux-s390@vger.kernel.org, brueckner@linux.vnet.com, gregkh@linuxfoundation.org, heiko.carstens@de.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Hendrik Brueckner , schwidefsky@de.ibm.com, jslaby@suse.cz List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Oct 16, 2013 at 06:21:12PM -0500, Benjamin Herrenschmidt wrote: > 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 ? That's possible. The only concern is that the tiocmset() callback could be triggered from within the hvc_console() layer as well as from user space via ioctl. For the hvc_iucv driver, I do not want to introduce this ioctl. One option would be to add parameter to the hvc_callbacks that indicate the origin so that a backend could filter. > 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.. Sure the hvc_console layer could do as much as possible. > > None of that is urgent or anything, it's just odd and would be nice to cleanup. Thanks and kind regards, Hendrik