Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752845AbbGNMuh (ORCPT ); Tue, 14 Jul 2015 08:50:37 -0400 Received: from mail-lb0-f171.google.com ([209.85.217.171]:36648 "EHLO mail-lb0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751617AbbGNMuf (ORCPT ); Tue, 14 Jul 2015 08:50:35 -0400 Subject: Re: [PATCH 1/2] isdn/gigaset: reset tty->receive_room when attaching ser_gigaset To: Tilman Schmidt , Paul Bolle References: Cc: netdev@vger.kernel.org, David Miller , Peter Hurley , Hansjoerg Lipp , linux-kernel@vger.kernel.org From: Sergei Shtylyov Message-ID: <55A50598.6090909@cogentembedded.com> Date: Tue, 14 Jul 2015 15:50:32 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2177 Lines: 58 Hello. On 7/14/2015 1:37 AM, Tilman Schmidt wrote: > 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); > - Unrelated change? > 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; The general kernel coding style is to surround operators with spaces. [...] MBR, Sergei -- 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/