From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9BE01C43387 for ; Sun, 16 Dec 2018 22:12:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7506B2082F for ; Sun, 16 Dec 2018 22:12:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730999AbeLPWMq (ORCPT ); Sun, 16 Dec 2018 17:12:46 -0500 Received: from mail-out.m-online.net ([212.18.0.9]:56752 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730758AbeLPWMq (ORCPT ); Sun, 16 Dec 2018 17:12:46 -0500 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 43Hz6z1WgLz1qxPv; Sun, 16 Dec 2018 23:12:42 +0100 (CET) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 43Hz6y5wPDz1qqkw; Sun, 16 Dec 2018 23:12:42 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id NtzQMBRQDqFe; Sun, 16 Dec 2018 23:12:41 +0100 (CET) X-Auth-Info: SuV4hhHjKXsIQAhuxtjZrRLxUwhb+gg08wM5UmNwOE4= Received: from [IPv6:::1] (unknown [195.140.253.167]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Sun, 16 Dec 2018 23:12:41 +0100 (CET) Subject: Re: [PATCH] Revert "serial: 8250: Fix clearing FIFOs in RS485 mode again" To: Ezequiel Garcia Cc: Paul Burton , "linux-serial@vger.kernel.org" , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" , Paul Burton , Daniel Jedrychowski , "linux-mips@vger.kernel.org" , stable , Ezequiel Garcia References: <20181213174834.kxdy6fphaeoivqgh@pburton-laptop> <20181216200833.27928-1-paul.burton@mips.com> <20181216213133.kwe24pif3v4wcgwp@pburton-laptop> <949fdd3d-535e-d235-f406-d5bde4658c5e@denx.de> From: Marek Vasut Message-ID: Date: Sun, 16 Dec 2018 23:11:43 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 12/16/2018 10:52 PM, Ezequiel Garcia wrote: > On Sun, 16 Dec 2018 at 18:45, Marek Vasut wrote: > [skips discussion] >> >>> Ultimately it's Greg's decision but it sounds like you're asking me to >>> say it's OK to break the JZ4780 in a stable kernel with a patch that I >>> think would be risky anyway, and I won't do that. >> >> I am saying this revert breaks AM335x, so this is a stalemate. I had a >> discussion with Ezequiel (on CC) and he seems to have a different >> smaller patch coming for this problem. >> > > Can you guys test this? Note that serial8250_do_startup has a comment > stating clearly that it has the intention of disabling the FIFOs, > so it seems this is the right thing to do. > > Paul, this removes the garbage on my CI20 (rev.1) > > diff --git a/drivers/tty/serial/8250/8250_port.c > b/drivers/tty/serial/8250/8250_port.c > index c39482b96111..fac19cbc51d1 100644 > --- a/drivers/tty/serial/8250/8250_port.c > +++ b/drivers/tty/serial/8250/8250_port.c > @@ -2209,10 +2209,11 @@ int serial8250_do_startup(struct uart_port *port) > /* > * Clear the FIFO buffers and disable them. > * (they will be reenabled in set_termios()) > */ > serial8250_clear_fifos(up); > + serial_out(up, UART_FCR, 0); > > /* > * Clear the interrupt registers. > */ > serial_port_in(port, UART_LSR); > > On AM335x pocketbeagle Tested-by: Marek Vasut -- Best regards, Marek Vasut