From nobody Sun Feb 8 18:17:16 2026 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 9F376E74901 for ; Mon, 2 Oct 2023 18:09:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238752AbjJBSJh (ORCPT ); Mon, 2 Oct 2023 14:09:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238744AbjJBSJd (ORCPT ); Mon, 2 Oct 2023 14:09:33 -0400 Received: from mail-qk1-x730.google.com (mail-qk1-x730.google.com [IPv6:2607:f8b0:4864:20::730]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6314C9 for ; Mon, 2 Oct 2023 11:09:30 -0700 (PDT) Received: by mail-qk1-x730.google.com with SMTP id af79cd13be357-774105e8c37so5614585a.3 for ; Mon, 02 Oct 2023 11:09:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hefring-com.20230601.gappssmtp.com; s=20230601; t=1696270170; x=1696874970; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=K/9udtHJxdUnIEfNuTeE6b1Yaqw4dJt+yBS5HPABR3I=; b=FXjpC1BfcbSAxOKwAOkJi1e5KiObsmqRyrZ1O755PF3BlijVsKtrR3kQOThxz/+a0k mVXmmmtNfc6ENPieANrBm/FwXLpuoi5mRikMgUENjRRlhiL43fcH+n7VWd+duBxzSCrj FKBb14j83CS2CamlUZBvccctthw1Aumqi1TEW2AyGYnuza60Qk2bzLWt3lIDmT8n7T3J ejMhEBkw/KrCOpdQmW4VVdx5xUpGKhOEFxsoufcQlzxlaqj9+P19GGQO0jEkXpc3UYgN E5Z+FXfq/OT/a1BkePzRvxfI9NZ7lJHqSiTv90gh7P1q/b9Q5PwtkYSqgYZMsVqDpBvd YAQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696270170; x=1696874970; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=K/9udtHJxdUnIEfNuTeE6b1Yaqw4dJt+yBS5HPABR3I=; b=Gx8Z/Qz0FpQkSy3upjSIC6eUD1ZVE1REQL3rxrTpgMmlgq0ZYB0XaoXZOaFLOgW46D t5IhFCyKICdv0P7ic+FP+42STNSlfVD+JtKfgkYda7/PueNQFzB2PGSSteNbkEd/bl3W ijNarNZoiRG2SkTLaV5FgH9qqjvAW+DTsaDfTy1ofRdTnvHL9uwXDhzIA2P8TN65CazM MKRbjWNArPUg0TtTbhdUsethdxnDJy05VdlldOREzCYI9/GE1QRjlZACIfqgQfEd0Y6S sXa8QuXlAA0ytY8Vq3+/EhlSQnEEvUCnWAoEk7KEiFvn6F+jtL1GwyGPHm+p+g/4fqf9 B58Q== X-Gm-Message-State: AOJu0Yy9Q1pnCFgC48M9nFmbGwjSLM77OVEKeKFZEbYW8puWcoMnBCf/ GtBqlOEHko5MN4BeI0lyIqFtmg== X-Google-Smtp-Source: AGHT+IGwixskDpdw9/a1WqqdPBN+k/f7EbXZs8t1/jSWdyRBC7cYwnhvEjFKQCihuGojDRTAfr1XbA== X-Received: by 2002:a05:620a:b5a:b0:770:9bd2:b3be with SMTP id x26-20020a05620a0b5a00b007709bd2b3bemr11139670qkg.5.1696270170028; Mon, 02 Oct 2023 11:09:30 -0700 (PDT) Received: from localhost.localdomain ([50.212.55.89]) by smtp.gmail.com with ESMTPSA id w15-20020ae9e50f000000b0077423f849c3sm7390255qkf.24.2023.10.02.11.09.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 11:09:29 -0700 (PDT) From: Ben Wolsieffer To: linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org Cc: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Maxime Coquelin , Alexandre Torgue , Michael Turquette , Stephen Boyd , Ben Wolsieffer Subject: [PATCH 1/2] clk: stm32: initialize syscon after clocks are registered Date: Mon, 2 Oct 2023 14:08:53 -0400 Message-ID: <20231002180854.1603452-2-ben.wolsieffer@hefring.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231002180854.1603452-1-ben.wolsieffer@hefring.com> References: <20231002180854.1603452-1-ben.wolsieffer@hefring.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The stm32-power-config syscon (PWR peripheral) is used in this driver and the STM32 RTC driver to enable write access to backup domain registers. The syscon's clock has a gate controlled by this clock driver, but this clock is currently not registered in the device tree. This only happens to work currently because all relevant clock setup and RTC initialization happens before clk_disabled_unused(). After this point, all syscon register writes are ignored. If we simply add the syscon clock in the device tree, we end up with a circular dependency because the clock has not been registered at the point this driver requests the syscon. This patch avoids this circular dependency by moving the syscon lookup after the clocks are registered. This does appear to create a possible race condition where someone could attempt to perform an operation on a backup domain clock before the syscon has been initialized. This would result in the operation having no effect because backup domain writes could not be enabled. I'm not sure if this is a problem or if there is a way to avoid it. Signed-off-by: Ben Wolsieffer --- drivers/clk/clk-stm32f4.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c index 07c13ebe327d..a88e762d2b5e 100644 --- a/drivers/clk/clk-stm32f4.c +++ b/drivers/clk/clk-stm32f4.c @@ -1697,12 +1697,6 @@ static void __init stm32f4_rcc_init(struct device_no= de *np) return; } =20 - pdrm =3D syscon_regmap_lookup_by_phandle(np, "st,syscfg"); - if (IS_ERR(pdrm)) { - pdrm =3D NULL; - pr_warn("%s: Unable to get syscfg\n", __func__); - } - match =3D of_match_node(stm32f4_of_match, np); if (WARN_ON(!match)) return; @@ -1894,6 +1888,12 @@ static void __init stm32f4_rcc_init(struct device_no= de *np) =20 of_clk_add_hw_provider(np, stm32f4_rcc_lookup_clk, NULL); =20 + pdrm =3D syscon_regmap_lookup_by_phandle(np, "st,syscfg"); + if (IS_ERR(pdrm)) { + pdrm =3D NULL; + pr_warn("%s: Unable to get syscfg\n", __func__); + } + return; fail: kfree(clks); --=20 2.42.0