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 304CCC43334 for ; Fri, 10 Jun 2022 10:03:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346749AbiFJKDi (ORCPT ); Fri, 10 Jun 2022 06:03:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348385AbiFJKDZ (ORCPT ); Fri, 10 Jun 2022 06:03:25 -0400 Received: from mx01.omp.ru (mx01.omp.ru [90.154.21.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23BADB1C24; Fri, 10 Jun 2022 03:03:21 -0700 (PDT) Received: from [192.168.1.103] (178.176.78.53) by msexch01.omp.ru (10.188.4.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.986.14; Fri, 10 Jun 2022 13:03:10 +0300 Subject: Re: [PATCH v4 2/8] clk: vc5: Fix 5P49V6901 outputs disabling when enabling FOD To: Serge Semin , Stephen Boyd , Philipp Zabel , Michael Turquette , Luca Ceresoli , Marek Vasut CC: Serge Semin , Alexey Malahov , Pavel Parkhomenko , Thomas Bogendoerfer , , , , Stephen Boyd References: <20220610072124.8714-1-Sergey.Semin@baikalelectronics.ru> <20220610072124.8714-3-Sergey.Semin@baikalelectronics.ru> From: Sergey Shtylyov Organization: Open Mobile Platform Message-ID: Date: Fri, 10 Jun 2022 13:03:10 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20220610072124.8714-3-Sergey.Semin@baikalelectronics.ru> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [178.176.78.53] X-ClientProxiedBy: msexch01.omp.ru (10.188.4.12) To msexch01.omp.ru (10.188.4.12) X-KSE-ServerInfo: msexch01.omp.ru, 9 X-KSE-AntiSpam-Interceptor-Info: scan successful X-KSE-AntiSpam-Version: 5.9.20, Database issued on: 06/10/2022 09:45:43 X-KSE-AntiSpam-Status: KAS_STATUS_NOT_DETECTED X-KSE-AntiSpam-Method: none X-KSE-AntiSpam-Rate: 59 X-KSE-AntiSpam-Info: Lua profiles 171050 [Jun 10 2022] X-KSE-AntiSpam-Info: Version: 5.9.20.0 X-KSE-AntiSpam-Info: Envelope from: s.shtylyov@omp.ru X-KSE-AntiSpam-Info: LuaCore: 489 489 b67d2e276d358fa514f5991440453e6a402e3a26 X-KSE-AntiSpam-Info: {rep_avail} X-KSE-AntiSpam-Info: {Tracking_from_domain_doesnt_match_to} X-KSE-AntiSpam-Info: {relay has no DNS name} X-KSE-AntiSpam-Info: {SMTP from is not routable} X-KSE-AntiSpam-Info: {Found in DNSBL: 178.176.78.53 in (user) b.barracudacentral.org} X-KSE-AntiSpam-Info: omp.ru:7.1.1;127.0.0.199:7.1.2;178.176.78.53:7.1.2,7.4.1,7.7.3;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1 X-KSE-AntiSpam-Info: {iprep_blacklist} X-KSE-AntiSpam-Info: ApMailHostAddress: 178.176.78.53 X-KSE-AntiSpam-Info: {DNS response errors} X-KSE-AntiSpam-Info: Rate: 59 X-KSE-AntiSpam-Info: Status: not_detected X-KSE-AntiSpam-Info: Method: none X-KSE-AntiSpam-Info: Auth:dmarc=temperror header.from=omp.ru;spf=temperror smtp.mailfrom=omp.ru;dkim=none X-KSE-Antiphishing-Info: Clean X-KSE-Antiphishing-ScanningType: Heuristic X-KSE-Antiphishing-Method: None X-KSE-Antiphishing-Bases: 06/10/2022 09:48:00 X-KSE-AttachmentFiltering-Interceptor-Info: protection disabled X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: Clean, bases: 6/10/2022 8:39:00 AM X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 6/10/22 10:21 AM, Serge Semin wrote: > We have discovered random glitches during the system boot up procedure. > The problem investigation led us to the weird outcomes: when none of the > Renesas 5P49V6901 ports are explicitly enabled by the kernel driver, the > glitches disappeared. It was a mystery since the SoC external clock > domains were fed with different 5P49V6901 outputs. The driver code didn't > seem like bogus either. We almost despaired to find out a root cause when > the solution was found for a more modern revision of the chip. It turned > out the 5P49V6901 clock generator stopped its output for a short period of > time during the VC5_OUT_DIV_CONTROL register writing. The same problem has > was found for the 5P49V6965 revision of the chip and the was successfully s/was found/been found/, s/the was/that was/? > fixed in commit fc336ae622df ("clk: vc5: fix output disabling when > enabling a FOD") by enabling the "bypass_sync" flag hidden inside "Unused > Factory Reserved Register". Even though the 5P49V6901 registers > description and programming guide doesn't provide any intel regarding that > flag, setting it up anyway in the officially unused register completely > eliminated the denoted glitches. Thus let's activate the functionality > submitted in commit fc336ae622df ("clk: vc5: fix output disabling when > enabling a FOD") for the Renesas 5P49V6901 chip too in order to remove > the ports implicit inter-dependency. > > Fixes: dbf6b16f5683 ("clk: vc5: Add support for IDT VersaClock 5P49V6901") > Signed-off-by: Serge Semin [...] MBR, Sergey