From patchwork Thu Jul 28 10:57:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 12931099 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 6DB2CC3F6B0 for ; Thu, 28 Jul 2022 10:58:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236656AbiG1K6C (ORCPT ); Thu, 28 Jul 2022 06:58:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236578AbiG1K55 (ORCPT ); Thu, 28 Jul 2022 06:57:57 -0400 Received: from mail.baikalelectronics.com (unknown [87.245.175.230]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0ACF161136; Thu, 28 Jul 2022 03:57:49 -0700 (PDT) Received: from mail (mail.baikal.int [192.168.51.25]) by mail.baikalelectronics.com (Postfix) with ESMTP id 738B216CC; Thu, 28 Jul 2022 14:00:11 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.baikalelectronics.com 738B216CC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baikalelectronics.ru; s=mail; t=1659006011; bh=BveNLPY/YG4fFAd5N/AaPUO76c/YnxfM372ERsi7TmM=; h=From:To:CC:Subject:Date:In-Reply-To:References:From; b=bGCljDdsVryxjaz0biJCv36iFs44c720g/ck2YmtYO3ML7Lv+zvZG44Zuio+jmV7V oMFD7fWLwRi4RNHvNfoXZnK6p/BTVFrjVBGJW6FL0oV5AOoJVu6ef5ZuECc7mpkosO 0J1t7GYS3eiBI9rUvx7OvBphKkhP8VxGdQIk0hqM= Received: from localhost (192.168.53.207) by mail (192.168.51.25) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Thu, 28 Jul 2022 13:57:46 +0300 From: Serge Semin To: Stephen Boyd , Michael Turquette , Luca Ceresoli , Marek Vasut CC: Serge Semin , Serge Semin , Alexey Malahov , Pavel Parkhomenko , Philipp Zabel , Thomas Bogendoerfer , , , , Stephen Boyd Subject: [PATCH v9 1/7] clk: vc5: Fix 5P49V6901 outputs disabling when enabling FOD Date: Thu, 28 Jul 2022 13:57:29 +0300 Message-ID: <20220728105736.8266-2-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20220728105736.8266-1-Sergey.Semin@baikalelectronics.ru> References: <20220728105736.8266-1-Sergey.Semin@baikalelectronics.ru> MIME-Version: 1.0 X-ClientProxiedBy: MAIL.baikal.int (192.168.51.25) To mail (192.168.51.25) Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org 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 has been 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 was found for the 5P49V6965 revision of the chip and was successfully 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 Reviewed-by: Luca Ceresoli --- Changelog v4: - This is a new patch added on v4 lap of the series. Changelog v5: - Fix some grammar mistakes in the commit log. (@Sergey Shtylyov) --- drivers/clk/clk-versaclock5.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c index e7be3e54b9be..03cfef494b49 100644 --- a/drivers/clk/clk-versaclock5.c +++ b/drivers/clk/clk-versaclock5.c @@ -1204,7 +1204,7 @@ static const struct vc5_chip_info idt_5p49v6901_info = { .model = IDT_VC6_5P49V6901, .clk_fod_cnt = 4, .clk_out_cnt = 5, - .flags = VC5_HAS_PFD_FREQ_DBL, + .flags = VC5_HAS_PFD_FREQ_DBL | VC5_HAS_BYPASS_SYNC_BIT, }; static const struct vc5_chip_info idt_5p49v6965_info = {