From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932880Ab2JWJ4c (ORCPT ); Tue, 23 Oct 2012 05:56:32 -0400 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:49934 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932503Ab2JWJ4a (ORCPT ); Tue, 23 Oct 2012 05:56:30 -0400 Date: Tue, 23 Oct 2012 11:01:33 +0100 From: Alan Cox To: Min Zhang Cc: gregkh@linuxfoundation.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] serial: 8250 check iir rdi in interrupt Message-ID: <20121023110133.62bed522@pyramind.ukuu.org.uk> In-Reply-To: References: X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Added module parameter skip_rdi_check to opt out this workaround. NAK. Anything like this should be runtime. > Tested on Radisys ATCA 46XX which uses FPGA 16550-compatible and > other generic 16550 UART. It takes from an hour to days to reproduce by > pumping inputs to serial console continously using TeraTerm script: You turn this on by default but it's a nasty IRQ latency penalty on a lot of x86 platforms with the uarts on the lpc bus. What I am not clear on from this is - do you see it on both the ports (the bug that is) - if you do see it on both are you sure its not in reality a symptom of some other console/irq handling race ? Alan