From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH] serial/mxs-auart: increase time to wait for transmitter to become idle Date: Thu, 4 Jul 2013 18:02:50 +0200 Message-ID: <20130704160250.GC32260@pengutronix.de> References: <1372413017-23252-1-git-send-email-u.kleine-koenig@pengutronix.de> <20130704092716.GC17454@pengutronix.de> <20130704155836.GA13897@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:46113 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756525Ab3GDQC4 (ORCPT ); Thu, 4 Jul 2013 12:02:56 -0400 Content-Disposition: inline In-Reply-To: <20130704155836.GA13897@kroah.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-serial@vger.kernel.org, kernel@pengutronix.de, stable@vger.kernel.org Hi Greg, On Thu, Jul 04, 2013 at 08:58:36AM -0700, Greg Kroah-Hartman wrote: > On Thu, Jul 04, 2013 at 11:27:16AM +0200, Uwe Kleine-K=F6nig wrote: > > On Fri, Jun 28, 2013 at 11:49:41AM +0200, Uwe Kleine-K=F6nig wrote: > > > Without this patch the driver waits ~1 ms for the UART to become = idle. At > > > 115200n8 this time is (theoretically) enough to transfer 11.5 cha= racters > > > (=3D 115200 bits/s / (10 Bits/char) * 1ms). As the mxs-auart has = a fifo size > > > of 16 characters the clock is gated too early. The problem is wor= se for > > > lower baud rates. > > >=20 > > > This only happens to really shut down the transmitter in the midd= le of a > > > transfer if /dev/ttyAPPx isn't opened in userspace (e.g. by a get= ty) but > > > was at least once (because the bootloader doesn't disable the tra= nsmitter). > > >=20 > > > So increase the timeout to 20 ms which should be enough for 9600n= 8, too. > > > Moreover skip gating the clock if the timeout is elapsed. > > >=20 > > > Cc: stable@vger.kernel.org # v2.6.39+ > > > Signed-off-by: Uwe Kleine-K=F6nig > > Any comments on this. I hoped this patch would make it in for 3.10 = :-( >=20 > You sent it after my tree closed for 3.11, 3.10 is a stretch :) You close your tree for fixes? Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= | -- To unsubscribe from this list: send the line "unsubscribe linux-serial"= in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html