From patchwork Fri Jun 10 07:21:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 12876611 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 7BBB8CCA47F for ; Fri, 10 Jun 2022 07:30:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346940AbiFJHaU (ORCPT ); Fri, 10 Jun 2022 03:30:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347022AbiFJHaE (ORCPT ); Fri, 10 Jun 2022 03:30:04 -0400 Received: from mail.baikalelectronics.com (mail.baikalelectronics.com [87.245.175.230]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B37DB21AE; Fri, 10 Jun 2022 00:30:01 -0700 (PDT) Received: from mail (mail.baikal.int [192.168.51.25]) by mail.baikalelectronics.com (Postfix) with ESMTP id 9D1BCBD3; Fri, 10 Jun 2022 10:22:24 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.baikalelectronics.com 9D1BCBD3 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baikalelectronics.ru; s=mail; t=1654845745; bh=/ATpPn5tsZ4m5LXVjUB+s2xJExFcZUwfGGYs9UuBRm0=; h=From:To:CC:Subject:Date:In-Reply-To:References:From; b=rED/PiOtEGQlT6B72rH4m9mv6LGMvLGiQSaD9co31gQi+glvLXrXBaXaXP25QzUVA G7pu13gfID8vrbqTeaacGQhBDKcju+YxwwWx1gcFaT2Gyzdc3SuQIwNdap2xiUTsry GZ9XqLzxjNgr1JXIzKaqaQtXmceyPUpPDnqMwASs= Received: from localhost (192.168.53.207) by mail (192.168.51.25) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Fri, 10 Jun 2022 10:21:32 +0300 From: Serge Semin To: Stephen Boyd , Philipp Zabel , Michael Turquette , Luca Ceresoli , Marek Vasut CC: Serge Semin , Serge Semin , Alexey Malahov , Pavel Parkhomenko , Thomas Bogendoerfer , , , , Stephen Boyd Subject: [PATCH v4 2/8] clk: vc5: Fix 5P49V6901 outputs disabling when enabling FOD Date: Fri, 10 Jun 2022 10:21:18 +0300 Message-ID: <20220610072124.8714-3-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20220610072124.8714-1-Sergey.Semin@baikalelectronics.ru> References: <20220610072124.8714-1-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 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 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 Reviewed-by: Luca Ceresoli --- Changelog v4: - This is a new patch added on v4 lap of the series. --- 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 = {