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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 53ACFC6FD1C for ; Fri, 24 Mar 2023 13:08:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=y6JtZaSxQY2xIdQSwwp0dAd+BGlIIvZN8JfsqNu6WHQ=; b=a71ayykL9pTq5o 8BDKC7GVRalJjpagQPS3/eXhJQEglbZOhuoOh5Q5csG72uK2EE8Mav3AvJQFU6g9vGMhzUf91Duqs zhSo4YCj+6hgSgvbx3Hx6sbgQINxINxQD6c3GWOw8swjCWJ7DUTqsQ9WsWU6+lTOFLXCqbmm8l2KF SfVhh8bhoTF2rL1/saqhq1d8AfSjlm44q4tGwHalOX5K3q82IMGq/In+i+KoeHcidnr9NT1IPNqH5 l2jrkX5V+AlmDbXTFYoEt1Mf915xEtbse8Iof+xp3N/wdrJuWeOAO8/dquLTAhMv2Dyaryc282dsn SsCjclsmbcKVQQ2VZggw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pfh8M-004RSf-0U; Fri, 24 Mar 2023 13:07:06 +0000 Received: from mail11.truemail.it ([2001:4b7e:0:8::81]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1pfh8J-004RRu-0r for linux-arm-kernel@lists.infradead.org; Fri, 24 Mar 2023 13:07:04 +0000 Received: from francesco-nb.int.toradex.com (93-49-2-63.ip317.fastwebnet.it [93.49.2.63]) by mail11.truemail.it (Postfix) with ESMTPA id 0D1832065E; Fri, 24 Mar 2023 14:07:01 +0100 (CET) Date: Fri, 24 Mar 2023 14:06:55 +0100 From: Francesco Dolcini To: Stefan Wahren Cc: Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Francesco Dolcini , Tomasz =?utf-8?Q?Mo=C5=84?= , Greg Kroah-Hartman , Jiri Slaby , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Sergey Organov , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , linux-serial , Linux ARM , Shawn Guo , Stefan Wahren Subject: Re: Regression: serial: imx: overrun errors on debug UART Message-ID: References: <2c29454b-9369-4360-8eb4-c151f59460cb@i2se.com> <989d6a6f-fd4d-3e53-d417-ddf71ccf7af@linux.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230324_060703_475219_F8C77596 X-CRM114-Status: GOOD ( 18.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Mar 24, 2023 at 01:49:56PM +0100, Stefan Wahren wrote: > Am 24.03.23 um 13:35 schrieb Ilpo J=E4rvinen: > > On Fri, 24 Mar 2023, Francesco Dolcini wrote: > > > On Fri, Mar 24, 2023 at 01:47:59PM +0200, Ilpo J=E4rvinen wrote: > > > > On Fri, 24 Mar 2023, Stefan Wahren wrote: > > > > > after switching to Linux 6.1.21 on our Tarragon board (i.MX6ULL S= oC), we > > > > > experience the following issues with the debug UART (115200 baud,= 8N1, no > > > > > hardware flow control): > > > > > = > > > > > - overrun errors if we paste in multiple text lines while system = is idle > > > > > - no reaction to single key strokes while system is on higher load > > > > > = > > > > > After reverting 7a637784d517 ("serial: imx: reduce RX interrupt f= requency") > > > > > the issue disappear. > > > > > = > > > > > Maybe it's worth to mention that the Tarragon board uses two addi= tional > > > > > application UARTs with similiar baud rates (9600 - 115200 baud, n= o hardware > > > > > flow control) for RS485 communication, but there are no overrun e= rrors (with > > > > > and without the mention change). > > > > This has come up earlier, see e.g.: > > > > = > > > > https://lore.kernel.org/linux-serial/20221003110850.GA28338@frances= co-nb.int.toradex.com/ > > > yep, it looks exactly the same issue. > > > = > > > We did not verify if this was affecting other UARTs. However, isn't R= S485 > > > half-duplex? > > While half-duplex is more likely by far due simplicity, RS485 could also > > be full-duplex. It seems imx driver supports for both modes. > = > The RS485 on Tarragon is half-duplex, but this is implemented in external > hardware. So from Linux / driver point of view it's a RS232. To me this is an interesting difference that might be worth investigating. The console is somehow special since you are going to echo out the received chars most of the times. Francesco _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel