Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752359Ab0FCMXP (ORCPT ); Thu, 3 Jun 2010 08:23:15 -0400 Received: from buzzloop.caiaq.de ([212.112.241.133]:52331 "EHLO buzzloop.caiaq.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751992Ab0FCMXO (ORCPT ); Thu, 3 Jun 2010 08:23:14 -0400 Date: Thu, 3 Jun 2010 14:23:09 +0200 From: Daniel Mack To: Alan Cox Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Johan Hovold , linux-usb@vger.kernel.org Subject: Re: [PATCH] usb-serial/ftdi_sio: fix DTR/RTS line modes Message-ID: <20100603122309.GJ2698@buzzloop.caiaq.de> References: <1275566102-5613-1-git-send-email-daniel@caiaq.de> <20100603123225.55f544ff@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100603123225.55f544ff@linux.intel.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1471 Lines: 36 On Thu, Jun 03, 2010 at 12:32:25PM +0100, Alan Cox wrote: > On Thu, 3 Jun 2010 13:55:02 +0200 > Daniel Mack wrote: > > > Call set_mctrl() and clear_mctrl() according to the flow control mode > > selected. This makes serial communication for FT232 connected devices > > work when CRTSCTS is not set. > > > > This fixes a regression introduced by 4175f3e31 ("tty_port: If we are > > opened non blocking we still need to raise the carrier"). This patch > > calls the low-level driver's dtr_rts() function which consequently > > sets TIOCM_DTR | TIOCM_RTS. A later call to set_termios() without > > CRTSCTS in cflags, however, does not reset these bits, and so data is > > not actually sent out on the serial wire. > > If you've got hardware the other end expecting RTS/CTS signals you > really ought to set CRTSCTS. I know. It is, however, a regression in my case, and there might be other cases where RTS/CTS aren't connected at all. The core of the problem is that the driver sets hardware flow control, even though the userspace asked for not doing that. > However you patch makes complete sense in > terms of which way it is best to end up. And it shouldn't break anything I'd say. Thanks, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/