From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Edwards Subject: tcflow(TCOON/TCOOFF) vs. received XON/XOFF characters Date: Wed, 16 Jul 2014 17:20:58 +0000 (UTC) Message-ID: Return-path: Received: from plane.gmane.org ([80.91.229.3]:57219 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933237AbaGPRVO (ORCPT ); Wed, 16 Jul 2014 13:21:14 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1X7StE-0005n8-Mx for linux-serial@vger.kernel.org; Wed, 16 Jul 2014 19:21:12 +0200 Received: from dsl.comtrol.com ([64.122.56.22]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 16 Jul 2014 19:21:12 +0200 Received: from grant.b.edwards by dsl.comtrol.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 16 Jul 2014 19:21:12 +0200 Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: linux-serial@vger.kernel.org I'm working on the regression test appliction I use to test the serial drivers I maintain, and I've run into a problem with interaction between tcflow(TCOON/TCOOFF) and XON/XOFF using bog-standard 16x50 UARTs and the normal in-kernel driver. When I call tcflow(TCOOFF) on a tty device and then write data to that tty device, the data isn't sent. That's what I expect. But, when an XON is then received by that port, it does not start the tx data. Conversly, when a serial port receives an XOFF, it stops sending data as it should, but a subsequent call to tcflow(TCOON) does not casue it to start sending data. Am I misunderstanding how tcflow(TCOxxx) is supposed to interact with XON/XOFF flow control? Or is something broken in the tty layer or uart driver? -- Grant Edwards grant.b.edwards Yow! This is a NO-FRILLS at flight -- hold th' CANADIAN gmail.com BACON!!