From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752740AbbGMXbp (ORCPT ); Mon, 13 Jul 2015 19:31:45 -0400 Received: from mail.pxnet.com ([89.1.7.7]:55415 "EHLO mail.pxnet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752605AbbGMXbk (ORCPT ); Mon, 13 Jul 2015 19:31:40 -0400 X-Greylist: delayed 3252 seconds by postgrey-1.27 at vger.kernel.org; Mon, 13 Jul 2015 19:31:36 EDT Message-Id: In-Reply-To: References: From: Tilman Schmidt Subject: [PATCH 1/2] isdn/gigaset: reset tty->receive_room when attaching ser_gigaset To: Paul Bolle Cc: netdev@vger.kernel.org, David Miller , Peter Hurley , Hansjoerg Lipp , linux-kernel@vger.kernel.org Date: Tue, 14 Jul 2015 00:37:13 +0200 (CEST) X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (mail.pxnet.com [IPv6:2001:4dd0:f004:7::7]); Tue, 14 Jul 2015 00:37:18 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 79901317ce80 ("n_tty: Don't flush buffer when closing ldisc"), first merged in kernel release 3.10, caused the following regression in the Gigaset M101 driver: Before that commit, when closing the N_TTY line discipline in preparation to switching to N_GIGASET_M101, receive_room would be reset to a non-zero value by the call to n_tty_flush_buffer() in n_tty's close method. With the removal of that call, receive_room might be left at zero, blocking data reception on the serial line. The present patch fixes that regression by setting receive_room to an appropriate value in the ldisc open method. Fixes: 79901317ce80 ("n_tty: Don't flush buffer when closing ldisc") Signed-off-by: Tilman Schmidt --- drivers/isdn/gigaset/ser-gigaset.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/drivers/isdn/gigaset/ser-gigaset.c b/drivers/isdn/gigaset/ser-gigaset.c index 8c91fd5..3ac9c41 100644 --- a/drivers/isdn/gigaset/ser-gigaset.c +++ b/drivers/isdn/gigaset/ser-gigaset.c @@ -524,9 +524,18 @@ gigaset_tty_open(struct tty_struct *tty) cs->hw.ser->tty = tty; atomic_set(&cs->hw.ser->refcnt, 1); init_completion(&cs->hw.ser->dead_cmp); - tty->disc_data = cs; + /* Set the amount of data we're willing to receive per call + * from the hardware driver to half of the input buffer size + * to leave some reserve. + * Note: We don't do flow control towards the hardware driver. + * If more data is received than will fit into the input buffer, + * it will be dropped and an error will be logged. This should + * never happen as the device is slow and the buffer size ample. + */ + tty->receive_room = RBUFSIZE/2; + /* OK.. Initialization of the datastructures and the HW is done.. Now * startup system and notify the LL that we are ready to run */ -- 1.7.1