From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: Mainline commit "serial: Test for no tx data on tx restart" not correct for i.MX6? Date: Wed, 23 Jul 2014 12:32:14 -0400 Message-ID: <53CFE38E.6070302@hurleysoftware.com> References: <53CF3599.6040509@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:45107 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758220AbaGWQcT (ORCPT ); Wed, 23 Jul 2014 12:32:19 -0400 In-Reply-To: <53CF3599.6040509@gmail.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Dirk Behme , linux-serial@vger.kernel.org, Huang Shijie Cc: Aaro Koskinen , Greg Kroah-Hartman , "Wang, Jiada" , Dirk Behme Hi Dirk, On 07/23/2014 12:10 AM, Dirk Behme wrote: > Hi, > > this is a question regarding the i.MX6 part (drivers/tty/serial/imx.c) of the commit > > serial: Test for no tx data on tx restart > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c557d392fbf5badd693ea1946a4317c87a26a716 > > Talking with some i.MX6 experts about this, I've got the comment > > -- cut -- > The imx serial driver part of this commit isn't correct > as imx.c sends x_char in irq handler, not in imx_start_tx(), > -- cut -- > > What do you think? Thanks for the comment. Yeah, I missed that the imx driver handled x_char _at all_, because how the imx driver is handling x_char looks broken. For example, if data is already in the tx ring buffer, imx_start_tx() will send that data before the x_char, and if all the tx ring buffer data is sent successfully, the tx interrupt is switched back off, so the x_char won't be sent. Also, the imx driver doesn't send x_char in dma mode? Regards, Peter Hurley