From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH] serial/mxs-auart: increase time to wait for transmitter to become idle Date: Thu, 4 Jul 2013 08:58:36 -0700 Message-ID: <20130704155836.GA13897@kroah.com> References: <1372413017-23252-1-git-send-email-u.kleine-koenig@pengutronix.de> <20130704092716.GC17454@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:47762 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752838Ab3GDP5p (ORCPT ); Thu, 4 Jul 2013 11:57:45 -0400 Content-Disposition: inline In-Reply-To: <20130704092716.GC17454@pengutronix.de> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Cc: Jiri Slaby , linux-serial@vger.kernel.org, kernel@pengutronix.de, stable@vger.kernel.org On Thu, Jul 04, 2013 at 11:27:16AM +0200, Uwe Kleine-K=F6nig wrote: > Hi Greg, >=20 > 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 id= le. At > > 115200n8 this time is (theoretically) enough to transfer 11.5 chara= cters > > (=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 worse= for > > lower baud rates. > >=20 > > This only happens to really shut down the transmitter in the middle= of a > > transfer if /dev/ttyAPPx isn't opened in userspace (e.g. by a getty= ) but > > was at least once (because the bootloader doesn't disable the trans= mitter). > >=20 > > So increase the timeout to 20 ms which should be enough for 9600n8,= 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 :-= ( You sent it after my tree closed for 3.11, 3.10 is a stretch :) I'll look at it after the 3.11-rc1 merge window is closed, give me a chance, I'm a bit busy for the next week or so with the fallout of that... thanks, greg k-h -- 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