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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7708C6FD1C for ; Fri, 24 Mar 2023 12:50:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230372AbjCXMuX (ORCPT ); Fri, 24 Mar 2023 08:50:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230366AbjCXMuW (ORCPT ); Fri, 24 Mar 2023 08:50:22 -0400 Received: from mout.kundenserver.de (mout.kundenserver.de [212.227.17.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3478EC3 for ; Fri, 24 Mar 2023 05:50:21 -0700 (PDT) Received: from [192.168.1.141] ([37.4.248.35]) by mrelayeu.kundenserver.de (mreue108 [212.227.15.183]) with ESMTPSA (Nemesis) id 1N95qT-1qa0dG1zGh-016BTG; Fri, 24 Mar 2023 13:49:57 +0100 Message-ID: Date: Fri, 24 Mar 2023 13:49:56 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: Regression: serial: imx: overrun errors on debug UART To: =?UTF-8?Q?Ilpo_J=c3=a4rvinen?= , Francesco Dolcini Cc: =?UTF-8?Q?Tomasz_Mo=c5=84?= , Greg Kroah-Hartman , Jiri Slaby , =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Sergey Organov , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , linux-serial , Linux ARM , Shawn Guo , Stefan Wahren References: <2c29454b-9369-4360-8eb4-c151f59460cb@i2se.com> <989d6a6f-fd4d-3e53-d417-ddf71ccf7af@linux.intel.com> Content-Language: en-US From: Stefan Wahren In-Reply-To: <989d6a6f-fd4d-3e53-d417-ddf71ccf7af@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:UTGPJEe3V9ioEcmae8BlQwxtxLaM5E16Qxnl7nAdZRYVT9JUy2j I6Z0x0NnHh6Km9snhoj17/ZEDc76c4JQWpdIMRt67FgIdJ9WeGtus8nL13LO/wg6e48z9oz Wl7IRsdftI79p3vTvjyr9yuMYUqpPk5vXzY01CVi+ADykr6QX52Kw/VwpyGxa/Mh8ZEY8YC khotX2Nu0JcGas2IagNoA== UI-OutboundReport: notjunk:1;M01:P0:36wpV76/2PA=;N9A0E2QyaxxHc/ketHn5umgaQR4 J/x/47m2i16nPU38E7Y4Gq3osar0RC5KIvLvQCkCpEEdKhiBHR2zeR1BUkeO8w+eaGf2dss6N jk/fkDO/8t5dgIJ4PJNJWen4iYrMqkkX5v1V2+h1623oEpqtSG6zRtBZZXcfO5t97NdGD31GE jpJiOVhhH9StKf3LDx1XZQtsVvqJbP5OJ1QcgCIQthaXBCsWhkvwBHYj0Ke4Ed+VygYDD0pdr DgN5p/IkmAQKr7d+3dIWKmmmMdbPXPPqd+fEQSdcvLuJz1ToMMILtOUqSdrmjsDadJO0gq3cT /RSjerSRESygvOvjBZDyCaleOODWibKMSZDgiX0kgw+lRJGX0K+T6irUpl+RR01qgydAdyfIu i4Pxj5QbTOW58TwllAtNSbrLIVbILJYZtc7Eymm8RgdGaqXNSwPgq9OkJmVdNolH8ZM4MtGUl mIiVs8z0434VyS3stGYBsSodUhI75drNgW1bZJrVMLf8qLVzUB6JOUpEJU7+9Ssb1ynNxETBc r10YTt8EzSkuiKB1AAGyc9mK6Zsubl2tFv2dVI5HafWQh5MyFbn4mVMd+yRJSKrW+huc83plr W1cI5J+4dD1pDCDHj9gTi7Wf64vMhfymIXuhgSWWuT5/9Oha6+bBfe6HkQ0zj/Fj9X6jJ6Kwb 6FkXI31iQMBeo2nBUlg4k0ZHUgsviL4/0dKu3qznFw== Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Am 24.03.23 um 13:35 schrieb Ilpo Järvinen: > On Fri, 24 Mar 2023, Francesco Dolcini wrote: > >> Hello >> >> On Fri, Mar 24, 2023 at 01:47:59PM +0200, Ilpo Järvinen wrote: >>> On Fri, 24 Mar 2023, Stefan Wahren wrote: >>>> after switching to Linux 6.1.21 on our Tarragon board (i.MX6ULL SoC), 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 frequency") >>>> the issue disappear. >>>> >>>> Maybe it's worth to mention that the Tarragon board uses two additional >>>> application UARTs with similiar baud rates (9600 - 115200 baud, no hardware >>>> flow control) for RS485 communication, but there are no overrun errors (with >>>> and without the mention change). >>> This has come up earlier, see e.g.: >>> >>> https://lore.kernel.org/linux-serial/20221003110850.GA28338@francesco-nb.int.toradex.com/ >> yep, it looks exactly the same issue. >> >> We did not verify if this was affecting other UARTs. However, isn't RS485 >> 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 us the current behavior (overrun errors and no reaction under load) is not acceptable. I agree that increasing the rx threshold isn't the real issue. But i needed a starting point for a discussion. So any ideas how to investigate this further are welcome. >