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 758F7C001DE for ; Wed, 9 Aug 2023 02:12:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229576AbjHICM1 (ORCPT ); Tue, 8 Aug 2023 22:12:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229521AbjHICM1 (ORCPT ); Tue, 8 Aug 2023 22:12:27 -0400 Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net [217.70.183.198]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 113BCF3; Tue, 8 Aug 2023 19:12:25 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 512ABC0003; Wed, 9 Aug 2023 02:12:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1691547144; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9rFEnNQwjkEYrsNofQX5zgngbo+/k9VPRl09iaDkgfw=; b=fM1JUYttGO4l1yPqT972IWNuJVhnctqVpdBXINuBxD+8nApZhrNa8mcnHMV4WKIHk8ap9B RqJ5YhliqSkKlnIcVDiysBN9l4D5u1V4IF2F+Y/CYYRRZ6OH1Voaj66uA99yBwWY2zDTHP eABokGOWzkeePett3NFaEAIJj+QFkFqEIATr+CoH8n9FcnIcEUBjlw8UZC28p3aiH0MeL3 /uss7CiOLllKYPt3QvzbgHE/9qZnyqW5OSQJcCL6SaBxk+EFqCGtgLNItpnaKOy2xbxKlb KTWsJ3/Amn7Kb1ttZbbpt/+CgSO4TudC/m+A074ZxLdZP1f85mHyUuU9uZo30g== Date: Wed, 9 Aug 2023 04:12:24 +0200 From: Alexandre Belloni To: Jacky Huang Cc: a.zummo@towertech.it, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, soc@kernel.org, mjchen@nuvoton.com, schung@nuvoton.com, Jacky Huang Subject: Re: [RESEND PATCH v2 3/3] rtc: Add driver for Nuvoton ma35d1 rtc controller Message-ID: <20230809021224ab4f229f@mail.local> References: <20230809011542.429945-1-ychuang570808@gmail.com> <20230809011542.429945-4-ychuang570808@gmail.com> <20230809021025a7c0daec@mail.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230809021025a7c0daec@mail.local> X-GND-Sasl: alexandre.belloni@bootlin.com Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 09/08/2023 04:10:27+0200, Alexandre Belloni wrote: > > +static int ma35d1_rtc_probe(struct platform_device *pdev) > > +{ > > + struct ma35_rtc *rtc; > > + struct clk *clk; > > + u32 regval; > > + int err; > > + > > + rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL); > > + if (!rtc) > > + return -ENOMEM; > > + > > + rtc->rtc_reg = devm_platform_ioremap_resource(pdev, 0); > > + if (IS_ERR(rtc->rtc_reg)) > > + return PTR_ERR(rtc->rtc_reg); > > + > > + clk = of_clk_get(pdev->dev.of_node, 0); > > + if (IS_ERR(clk)) > > + return dev_err_probe(&pdev->dev, PTR_ERR(clk), "failed to find rtc clock\n"); > > + > > + err = clk_prepare_enable(clk); > > + if (err) > > + return -ENOENT; > > + > > + platform_set_drvdata(pdev, rtc); > > + > > + rtc->rtcdev = devm_rtc_device_register(&pdev->dev, pdev->name, > > + &ma35d1_rtc_ops, THIS_MODULE); > > + if (IS_ERR(rtc->rtcdev)) > > + return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtcdev), > > + "failed to register rtc device\n"); > > This MUST be done last in probe, else you open a race with userspace. > > > > + > > + err = ma35d1_rtc_init(rtc, RTC_INIT_TIMEOUT); > > + if (err) > > + return err; > > + > > I don't believe you should do this on every probe but only when this > hasn't been done yet. > Also, if you can know that the time has never been set, don't discard this information, this is crucial information and it needs to be reported to userspace. -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com