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 0EB46C77B76 for ; Mon, 17 Apr 2023 18:41:55 +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-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=X2nJ9cJjpkAXmp5ECN9QBB8ooH1XEiKdnCgojoHBmtc=; b=ScfJZGUNn+ok/2 8zMpD5zcw9yyAJ5Kmt9VsHxjPCVoCVdqe2E6E/1ToULWPX31XrxPDnD1IrgZEb2FRwyeiWfTh7uUS 2hGRbyjASohqX1csS4QCV/a5EkE8To3ANrmsuPx9B4IJ4UqNcoW9KECc9N/HKzZP2Afq1Pfm8KAX4 OTCVNXWEpo0L3PXTDjM6rhOpytScxAZAYIG2sTmzTBpNqcx23jeR3k8X7xQHBW0IE3/dXW+JPwrCj oqnwUgJl3t0njDAi2VP2KgHz1LCj1TPagHR/0w5B4XgdZOTWYPCZsdkCyKz7VVqwZb8U3UbLFDUIX oaC6IvlnA6E7jj7yacqw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1poTmb-00HLko-0C; Mon, 17 Apr 2023 18:40:57 +0000 Received: from mout.kundenserver.de ([212.227.126.131]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1poTmX-00HLk6-0S for linux-arm-kernel@lists.infradead.org; Mon, 17 Apr 2023 18:40:55 +0000 Received: from [192.168.1.141] ([37.4.248.58]) by mrelayeu.kundenserver.de (mreue010 [212.227.15.167]) with ESMTPSA (Nemesis) id 1MG9Pg-1pY0hn0jdM-00GV4g; Mon, 17 Apr 2023 20:40:39 +0200 Message-ID: Date: Mon, 17 Apr 2023 20:40:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: Regression: serial: imx: overrun errors on debug UART To: Sergey Organov Cc: =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Fabio Estevam , =?UTF-8?Q?Ilpo_J=c3=a4rvinen?= , Stefan Wahren , linux-serial@vger.kernel.org, Greg Kroah-Hartman , Sascha Hauer , NXP Linux Team , Pengutronix Kernel Team , Shawn Guo , Jiri Slaby , =?UTF-8?Q?Tomasz_Mo=c5=84?= , Linux ARM References: <2c29454b-9369-4360-8eb4-c151f59460cb@i2se.com> <9e22f237-f3ee-0415-9e6b-89a137769b8f@i2se.com> <5d59dec6-9f6f-7b20-1221-f57c94b29cca@i2se.com> <20230325151100.mskydt3hwbnspqp4@pengutronix.de> <87mt3ynsa7.fsf@osv.gnss.ru> <87sfcy8ncu.fsf@osv.gnss.ru> Content-Language: en-US From: Stefan Wahren In-Reply-To: <87sfcy8ncu.fsf@osv.gnss.ru> X-Provags-ID: V03:K1:H/Lpb2ALEF/aoBYcVAS3im3ghqMoE08jRvi9RMG0+8RhWZb+834 BATV5zI+0LYEXE8G/hjguBVEbWqGiLAbcVibni1h7Zr0SdYhhON98N32Nv8MLmkI3uFhCLn 3ANmAFEhydtA9YmIzEHh14ChC+MpsWEOL7nN+2BaHLtnW2zcXYP/3O7mYUgoSPXSyoQJpAX i38fhLh2X8KVlldu39AlA== UI-OutboundReport: notjunk:1;M01:P0:F/zN/uh0lf4=;TWWErC1u83fff/b3rsPbtXcoCB1 VZLUIq7XL3SbtQoo9I9SWAtgXe0IYPWBoi5MhSJ3Map0ig4P4q+22ksfUASD4Qun0ZsaPrLN2 gnmm7aDRZ9zb3AQCIDUWtf/sHI9stsWzC9CLHHV/47yYwmJhCZ9ppNznbu1wrEhlUbqgyKdLa uedgaksQEk/JIGWv+7dU6zAyqg144U+oNnYKikPVZ0dsGlXRvuzKQgKclnTooiWBs2k/j5Sz2 FMOiKW6YkN+GKaBPSpOJiTPlMsT6h25Tysg+b95ka+zZh1dL7O6j7vT1LAzVJi1xY81yYkya/ W+8SEa56e+O8dp/Wxy2lgLdb7g1gv+DH5MtWFA64v2EfXdIs5sgwwFE9PJgn9UH8nqNYy8UoJ 8n19KoQOMGQiQT0Nq9Lt21Lq7GP3kxeHq7rk2Bh8etkwacEmCBz2hufLtIS+UfvJRlasWLazL LVyQDYJWQ+C9k6TSqfumWPsCsrSE7JirDaHekrlQPmppwTnoeYXczfGDS3ujD5WhUi+w3bqno OtxjoTIbaKOjAwHCifd0CKfcFr3sPLnjCRXbNpctwEhSCtDThZM/ZSXLcv9gN3PJKYoUN7xGe oSq0S299zFsHb7y5jqbFJCTl29fjyxxiJCqYmdRsMNQYEURlBS2sGgj6ltlGULaAKiscWFgGE HwkjRJdwlGVhQ8vL5DdQf8TRId9vJTRs0aL2lL+I4Q== X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230417_114053_488771_35E3E18B X-CRM114-Status: GOOD ( 16.51 ) 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Am 17.04.23 um 18:50 schrieb Sergey Organov: > Hi Stefan, > > Stefan Wahren writes: > >> Hi Sergey, >> > > [...] > >> i had some time today to investigate this a little bit. I thought it >> would be a good idea to use debugfs as a ugly quick hack: >> > > [...] > >> Using this i was able to better compare the behavior with RXTL_DEFAULT >> 1 (without overrun errors) and RXTL_DEFAULT 8 (with overrun errors) on >> my i.MX6ULL test platform. After doing my usual test scenario (copy >> some text lines to console) i got the following results: >> >> RXTL_DEFAULT 1 >> 21f0000.serial/stats:total_duration_us: 61 >> 21f0000.serial/stats:rx_duration_us: 36 >> 21f0000.serial/stats:tx_duration_us: 48 >> 21f0000.serial/stats:received: 28 >> 21f0000.serial/stats:send: 33 >> >> RXTL_DEFAULT 8 >> 21f0000.serial/stats:total_duration_us: 78 >> 21f0000.serial/stats:rx_duration_us: 46 >> 21f0000.serial/stats:tx_duration_us: 47 >> 21f0000.serial/stats:received: 33 >> 21f0000.serial/stats:send: 33 >> >> So based on the maximum of received characters on RX interrupt, i >> consider the root cause of this issue has already been there because >> the amount is near to the maximum of the FIFO (32 chars). So finally >> increasing RXTL_DEFAULT makes the situation even worse by adding >> enough latency for overrun errors. > > Yep, looks like an issue. > > What's the baud rate? 115200? Correct > If so, it means that interrupts are > apparently blocked in your system for up to about 28/(115200/10)=2.4 > milliseconds. This is very large number, and it may negatively affect > system performance in other places as well, I'm afraid. > > Best regards, > -- Sergey Organov > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel