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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 529AAC34031 for ; Tue, 18 Feb 2020 07:17:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 282892176D for ; Tue, 18 Feb 2020 07:17:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582010268; bh=TptrOmN9olc77EOFb55S0oGUJ2AnHnCIpyfBD4JXfpk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=yCrP15vkEZjoCKof20KGaQKhEa5y+2n7Jb9oRyiI6dvHQkYsNiUU3MnslDr7TqmDU axcxQDwfQMHqfPQdbECLEaFN3HXCCDORUzEynqtIitHVYnPeTMwiJmq+U9UfzQxYTx 5Ue6pUJ2SENBa+dNxC9oL+HbdV74SCwAyBqF79kg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726105AbgBRHRr (ORCPT ); Tue, 18 Feb 2020 02:17:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:39582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726072AbgBRHRr (ORCPT ); Tue, 18 Feb 2020 02:17:47 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7B597207FD; Tue, 18 Feb 2020 07:17:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582010266; bh=TptrOmN9olc77EOFb55S0oGUJ2AnHnCIpyfBD4JXfpk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JHwm9kzUgoWAlTQXwUpdpe6fhpgeX19c3Yxgc1Ga4x20dsQh2iWTkLYidTOBxENUG Sc16GXyFOlBH9qK+efHnhQySjDauwZR4hWaB6hSlvIBKbjJbYUJ+WDX8rvbOiqyII6 pgfBIpVWXe/JLq9FbNOCbv6MPEjohNsSzfgSH5FQ= Date: Tue, 18 Feb 2020 08:17:44 +0100 From: "gregkh@linuxfoundation.org" To: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Cc: Schrempf Frieder , "stable@vger.kernel.org" , "shawnguo@kernel.org" , "linux-kernel@vger.kernel.org" , "linux-serial@vger.kernel.org" Subject: Re: [PATCH 0/2] serial: imx: Backport fixes for irq handling to v4.14 Message-ID: <20200218071744.GA2087281@kroah.com> References: <20200217140740.29743-1-frieder.schrempf@kontron.de> <20200218045008.GA2049358@kroah.com> <20200218070310.ibv2m2f7ihfaevrp@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200218070310.ibv2m2f7ihfaevrp@pengutronix.de> Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Tue, Feb 18, 2020 at 08:03:10AM +0100, Uwe Kleine-König wrote: > On Tue, Feb 18, 2020 at 05:50:08AM +0100, gregkh@linuxfoundation.org wrote: > > On Mon, Feb 17, 2020 at 02:08:00PM +0000, Schrempf Frieder wrote: > > > From: Frieder Schrempf > > > > > > A customer of ours has problems with RS485 on i.MX6UL with the latest v4.14 > > > kernel. They get an exception like below from time to time (the trace is > > > from an older kernel, but the problem also exists in v4.14.170). > > > > > > As the cpuidle state 2 causes large delays for the interrupt that controls the > > > RS485 RTS signal (which can lead to collisions on the bus), cpuidle state 2 was > > > disabled on this system. This aspect might cause the exception happening more > > > often on this system than on other systems with default cpuidle settings. > > > > > > Looking for solutions I found Uwe's patches that were applied in v4.17 being > > > mentioned here [1] and here [2]. In [1] Uwe notes that backporting these fixes > > > to v4.14 might not be trivial, but I tried and in my opinion found it not to be > > > too problematic either. > > > > > > With the backported patches applied, our customer reports that the exceptions > > > stopped occuring. Given this and the fact that the problem seems to be known > > > and quite common, it would be nice to get this into the v4.14 stable tree. > > > > Thanks for the backports, both now queued up. > > To complete these fixes you also want to backport > > 101aa46bd221 serial: imx: fix a race condition in receive path If so, it needs to also go to 4.19.y, and someone needs to provide a working backport for both places :) thanks, greg k-h