From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932553AbbCIOg2 (ORCPT ); Mon, 9 Mar 2015 10:36:28 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:33832 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754245AbbCIOgW (ORCPT ); Mon, 9 Mar 2015 10:36:22 -0400 MIME-Version: 1.0 In-Reply-To: <1425907939.3838.182.camel@linux.intel.com> References: <54F96F5B.2090601@huawei.com> <54F9DACA.3020103@hurleysoftware.com> <54FD4779.3020902@huawei.com> <1425907939.3838.182.camel@linux.intel.com> Date: Mon, 9 Mar 2015 07:36:21 -0700 Message-ID: Subject: Re: [RFC] With 8250 Designware UART, if writes to the LCR failed the kernel will hung up From: Tim Kryger To: Alan Cox Cc: "long.wanglong" , Peter Hurley , Zhang Zhen , linux-serial@vger.kernel.org, Linux Kernel Mailing List , Tim Kryger , gregkh@linuxfoundation.org, Jamie Iles , Arnd Bergmann , shenjiangjiang@huawei.com, Wang Kai Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 9, 2015 at 6:32 AM, Alan Cox wrote: >> Maybe the next release of the board we will upgrade the serial block to the new version. >> but the issue is that how we circumvent this problem in kernel? > > What is the official vendor workaround ? They introduced a UART_16550_COMPATIBLE option for the IP which should be selected. If configured, writes to the LCR are allowed even if it is "busy" so there is no need to retry. More importantly there is no possibility of failing to write the LCR after numerous retries. -Tim