From nobody Tue Jun 16 05:02:02 2026 Received: from mail-dy1-f172.google.com (mail-dy1-f172.google.com [74.125.82.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4ED15246BBA for ; Thu, 16 Apr 2026 09:24:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776331470; cv=none; b=eLLPT7X65s5AyQr1mz9Lmq72Yyt3GToDCVf/2nIJuwrde8fuw/QTCXL6cLXErJxCewk7RgjqfdUrOXhg/EAzBIihMYQIse8uChlKRFa4CkxlZoMJO7EwK9K/zcJLMW60lgb7MoOwU13CduqQWAS2rSDb73pNJsJYh04jWcHP/H8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776331470; c=relaxed/simple; bh=paOrT4Um/61XT1noEDF5hTa2aMLicFVrvWEmzFdKUeM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HzMcAe62cWLcrLBcgYD1BcKVEOPKrSAk23bBpnuxtH68Z1HRjK1q7wmQp0zh/EO2ZTyztm6AijXKs3tliLuj1HoVvtS5HXVqhgPkxinRIzaPc/PlcfBj1/RxtyzsF8iAdvaU4WuWGMMaFlNW78bqwd8N8staaut4nBEzY49KPxw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=arista.com; spf=pass smtp.mailfrom=arista.com; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b=Fw9/Eyob; arc=none smtp.client-ip=74.125.82.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=arista.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arista.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="Fw9/Eyob" Received: by mail-dy1-f172.google.com with SMTP id 5a478bee46e88-2bda3b4318dso325779eec.1 for ; Thu, 16 Apr 2026 02:24:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; t=1776331468; x=1776936268; 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=7fdzF5y31CufKiwD2VPREbxrsOqwPtssoG5QIcGgix0=; b=Fw9/EyobMR437xaNAuD7amVOZJ4KmMqRj87I3Tr9/HK/OG2dOI2FBSn7STlOtxg4NA nYki6bYTwVIN45ZbYw/R+Pn1HXBvSpkXRxgSf2eUzN9+MHKdKWaseZ1OLhVzCEhzU4r/ P4KjlLERfI5Ywq8tUFL7TdIlQj0+BuG41kr/1wvEiS5wwWVawzwll9ucvx9UUcmGfYio ugc5eXJja5DzF5wwtyP9VPgMloxkGBP/oGAPFbSLUPNv4sKuadBZU9impxu6NWFdpGO2 9pJHZg8q12Hv9sSrSGbl+3g+yvxEa2MaqAjnFEOhChbpOzJOKQlJaSfz7LagELV2N5jR JQmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776331468; x=1776936268; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=7fdzF5y31CufKiwD2VPREbxrsOqwPtssoG5QIcGgix0=; b=FDqICs8cEo6FB0ryUISLufoIQxYF3KFstdJkNU+ndOe1hSyxXAJSGlw88y4d/mzoLB CZ1HcyA0kayMypYleY9r5bjtLmmQavvplb4OWjEm+B5iW/z/7FyppKzIvfOy1GAq4mNp /J9Jea5UsJ+q/EVZAyP6YKoFOBlz/95JkkiBOcbDBeEbyV5j2/IVhzpSWqstTMCV10jF 6vtK8tdeKu6qfmYVm0/rkgNLfR/GNoZyV3Z/vlESHFVBhW9inMOL/1Z4f3BR5tmbJtqP AuvRExmOL3+shyRUSX8yGdRem5X722BIsqKOFg11z21tQ9FXUCbpjUoiKSl2E2kg4fIS x0pQ== X-Forwarded-Encrypted: i=1; AFNElJ+0GfTnI65MXHAQTbOb8+aimFqdllm6b7PJlsCi0lB1Qc9sA7VHh7y5Rm2Rwzv5NmhI1L7L7IH+NZlCfks=@vger.kernel.org X-Gm-Message-State: AOJu0YzCgSnsCxkSgmua8KF6jaRpDQqcZn4HcDHrLzHDBFJc66GbLtN+ IhmX/U1zODnhaOdbRT2KERCFbdnuHA7ifUg7EebjYDDNLnqYRrEGbzEdiNxQplvaMA== X-Gm-Gg: AeBDieua/DI1UMAluNaGkLv7axuR8LlvLAx6Vsr5Q2RTiRnhJaCCtRhoUgPSl0127II RN5jepLS5PvTa+ECbJMytpgO8VtL6Thp39rLeuD9syCwQdtkoHnPht/YBSEw3HFymfkl5urISci o9tAgGzdXVdfA3DVn8RUzsJVXsTXh2fFRtHaimzKF6E3Xomz9uxEAIMGE8X8EVqcKu0QQOJxQSJ NpVJq9zcbEuRdpt6hzJhgO9QnyP3yIaeokZqD58HoFpvNWvt3GuFSwB/OQJGaBeHwkD36F+5qsC flJ2rpO3Nn841zmMkqDNG9cMSnGZF4nZ1sVOx9f9hVSok9KvRxJb3ALgOSZdEQapJ6KBu3iRz9B BVHcIqyNtHeGZn69m0HqQHZTAVlzNIStYQCs7nGUZSBJIBXeu+JxwPupqR/K78PbFkL6qlfSaMl GV9zMPlcLxBU/E0maK03sPTfuOtLc73cdAci60++MM4fXuXRfrNecUG6bVfhs= X-Received: by 2002:a05:7301:100a:b0:2cb:de38:c76f with SMTP id 5a478bee46e88-2de7c7615c9mr1268443eec.6.1776331468290; Thu, 16 Apr 2026 02:24:28 -0700 (PDT) Received: from adriana-schoodic-rtc.sjc.aristanetworks.com ([74.123.28.13]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2de8f965c5fsm6423815eec.26.2026.04.16.02.24.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2026 02:24:27 -0700 (PDT) From: Adriana Stancu To: alexandre.belloni@bootlin.com Cc: linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, Adriana Stancu Subject: [PATCH v1 1/2] dt-bindings: rtc: ti,bq32k: Add delay on rtc reads Date: Thu, 16 Apr 2026 02:24:13 -0700 Message-ID: <20260416092414.3210383-2-adriana@arista.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260416092414.3210383-1-adriana@arista.com> References: <20260416092414.3210383-1-adriana@arista.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a configurable device tree property to specify if a microseconds delay should be added before reading the RTC registers. Signed-off-by: Adriana Stancu --- Documentation/devicetree/bindings/rtc/ti,bq32000.yaml | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/Documentation/devicetree/bindings/rtc/ti,bq32000.yaml b/Docume= ntation/devicetree/bindings/rtc/ti,bq32000.yaml index bf9c1c4ddb7e..c7c2720a336b 100644 --- a/Documentation/devicetree/bindings/rtc/ti,bq32000.yaml +++ b/Documentation/devicetree/bindings/rtc/ti,bq32000.yaml @@ -29,6 +29,11 @@ properties: =20 trickle-diode-disable: true =20 + ti,read-settle-us: + default: 0 + description: + Delay in microseconds to wait before reading RTC registers. + required: - compatible - reg --=20 2.51.0 From nobody Tue Jun 16 05:02:02 2026 Received: from mail-dl1-f50.google.com (mail-dl1-f50.google.com [74.125.82.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3359739A051 for ; Thu, 16 Apr 2026 09:24:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.50 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776331473; cv=none; b=jXcoohWX3b/gix+8ugHF7vxwM3IB2O9rwkWV9PuciQem2vVS+0NUw8jM6sw1NLkUZ50aX81cXQQF+2Xt97QAfETLjtZ+aQYAtXh8J/Dk3B2x9g2iF1wN+KIleFj828DS7tlMP0mfzNS5YWhmvJDwGZNv0z7G8AuzDbYyoPeXMmc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776331473; c=relaxed/simple; bh=lpsJVVMGaMMep3FQ1HqvPEWk+behLL9g9H4dE1HgfXI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=l9/1UP+CFW7sugErzj4hyPJz9fIagCPznj/gvrVQ2SyuWcv4ZfAHwUZWyryB7CC1d0kFBSBDrDbPHe4uuqRNBJ6EuFeAKbgteEbAXqflAlQ76fBjAHu/KALyVYw/Xjaxe46sXfBOFM+y6YyfLmSkWkiopZut1hT1hfAb/uRXRKk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=arista.com; spf=pass smtp.mailfrom=arista.com; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b=ad9Ktzz4; arc=none smtp.client-ip=74.125.82.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=arista.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arista.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="ad9Ktzz4" Received: by mail-dl1-f50.google.com with SMTP id a92af1059eb24-124a7216c9cso493904c88.0 for ; Thu, 16 Apr 2026 02:24:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; t=1776331471; x=1776936271; 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=Qe0z97i7tkU8cjlRSgeT8EiRHH70cUTTYMxbnlOsLf8=; b=ad9Ktzz4QtydbqD00ELZka2jl4336M4sFJ2UWZcLr3g/yK2wwR9m0wcngU3N1SJbdl duyrXRRtjKZ9rkhUEK4diAmxOMvhE7N+3Cl3rRzTs3JFM7drvVo4QM+NHk7b3skKdt5T xkClmyJYkKf3LvUgRDOIvRKgyTMgQQZogJbAzGu28cyFGm6p9XwWgBzzST7Erc+BKPEb o8DUpToXCxH7/KCcs2HjfZS4Res9kmjMU6gOQ8/vLILhAh3tJb9EuuMYfGwXwQ5V1Vss zVFddqnxwTbBD/ZRg72UjJbIjWNMHp/RZNx+ZdI4JMY1fQSxwTrvC/ZzVEV6z4LSUMOC c7Jw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776331471; x=1776936271; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=Qe0z97i7tkU8cjlRSgeT8EiRHH70cUTTYMxbnlOsLf8=; b=l2x8LF5RVWG45XyRVyAM4Wv0cIPiuhQDBoh17vNGieGTymgBb4CefDMNcclU2knjdH IThiS8QAzKpxV957/Uk8dsbOh9sBxGO+SnI5BmiOU7h5XIqV14Wyvj+otgn6xSLIbiZp pcxvltT8tIgIHWuqv1Q3Ja/SLXynfh0vdsFAUwUpGhJqmcl51I40Wap3Yz2tXHJEYUi0 8hSIIokysI6D8CRbo0+cEFYVbc1o/BQ2t30eTHPHEKcUjfN0GuQTR20QXce0rrDeNcRz usKGfwDgd0WGlfOyoD/99iEcv00q3LM0EiFu/O5cKZ285UDbQBtYxVn0uW1SOu0wJPNI qRnA== X-Forwarded-Encrypted: i=1; AFNElJ/yaySF6sjtCz3+LahWfCELs7azhNvOfXcutyvrTA0Nj0H4vw5iXFFnf2kr5iRmAS8ujGjEKkprBF5dX0A=@vger.kernel.org X-Gm-Message-State: AOJu0YzcLao7uSD6UCXAFUrWpSplKERCRZciQR/xNUvRQ5StA0onabKA u044p3QFNsMSQK7kSIFMvOiv613Uyyx0gB6M0YilDFM8pnaXNaItOHWcNsh+MlW5Kg== X-Gm-Gg: AeBDietoB/h3MW1lHY4otdm4exPxb+xjdNCVf7M6RETzyCmdIxeTR0ngiGOwdCZFd5V PHxl+B+q0Okmw12aht14PSX2CCkHyPadD8iwYl6DW/eOnlUK7gm344SCNk2fMBcCQ3DW53ZZz1g 4MUSn518s6g51FEs356t1i8oFcMdvFcV0hoVGS6XbNAJUuaPrw2rmuqfCdWA/GvduIaEPx4mSsZ vU138xYacZ3uiuu5WMSishKAnsbko9sWSx8tnkA6QBynTToXH84LbLLDTTOmfNkU/PZvEdeqa7y ZhXRMboDfAkeYfVkEphVqZjWA4Y36sprWPdlXrctN5MaHrPctnWs8wMk+6SKH2E9SV+ojpPnjeu K01ckH0V2/+K8hJ0EaY/LSS1u/4XQeSOGP5X3Q7Tc+Bp/vU83QYBC/qugl3OVHLGM0WA1lK8/1+ XaOiV+BiGb5ZqAXXsZR16oJnMzob2lHlvVWGzcVW4q2XrBi08kTRnlz1h7yBg= X-Received: by 2002:a05:7300:f190:b0:2d5:eb89:4563 with SMTP id 5a478bee46e88-2e17d815c94mr377087eec.2.1776331470959; Thu, 16 Apr 2026 02:24:30 -0700 (PDT) Received: from adriana-schoodic-rtc.sjc.aristanetworks.com ([74.123.28.13]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2de8f965c5fsm6423815eec.26.2026.04.16.02.24.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2026 02:24:30 -0700 (PDT) From: Adriana Stancu To: alexandre.belloni@bootlin.com Cc: linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, Adriana Stancu Subject: [PATCH v1 2/2] rtc: bq32000: add configurable delay between RTC reads Date: Thu, 16 Apr 2026 02:24:14 -0700 Message-ID: <20260416092414.3210383-3-adriana@arista.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260416092414.3210383-1-adriana@arista.com> References: <20260416092414.3210383-1-adriana@arista.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When the RTC is used on systems without a interrupt line, userspace tools like `hwclock` fall back to a frequent polling loop to synchronize with the edge of the next second. On the BQ32000, this aggressive polling can temporarly lock the register refresh cycle, because the continuous transfers prevent the hardware from updating the buffer. This results in stale data reads or select() timeouts in userspace. This patch introduces a configurable settle delay via `ti,read-settle-us` property. If this property is specified, the driver uses a delay before reading the RTC registers. This provides a sufficient idle time for the hardware to sync with the register buffer. Signed-off-by: Adriana Stancu --- drivers/rtc/rtc-bq32k.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-) diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c index 7ad34539be4d..0cbfa0909732 100644 --- a/drivers/rtc/rtc-bq32k.c +++ b/drivers/rtc/rtc-bq32k.c @@ -16,6 +16,7 @@ #include #include #include +#include =20 #define BQ32K_SECONDS 0x00 /* Seconds register address */ #define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */ @@ -48,6 +49,11 @@ struct bq32k_regs { uint8_t years; }; =20 +struct bq32k_data { + struct rtc_device *rtc; + u32 read_delay_us; +}; + static struct i2c_driver bq32k_driver; =20 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t= len) @@ -89,9 +95,17 @@ static int bq32k_write(struct device *dev, void *data, u= int8_t off, uint8_t len) =20 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm) { + struct bq32k_data *bq32k =3D dev_get_drvdata(dev); struct bq32k_regs regs; int error; =20 + /* + * When the device doesn't have the interrupt connected, prevent + * userpace from polling the RTC registers to frequently. + */ + if (bq32k && bq32k->read_delay_us) + usleep_range(bq32k->read_delay_us, bq32k->read_delay_us + 50); + error =3D bq32k_read(dev, ®s, 0, sizeof(regs)); if (error) return error; @@ -253,13 +267,18 @@ static void bq32k_sysfs_unregister(struct device *dev) static int bq32k_probe(struct i2c_client *client) { struct device *dev =3D &client->dev; - struct rtc_device *rtc; + struct bq32k_data *bq32k; uint8_t reg; int error; + uint32_t settle_us =3D 0; =20 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) return -ENODEV; =20 + bq32k =3D devm_kzalloc(dev, sizeof(*bq32k), GFP_KERNEL); + if (!bq32k) + return -ENOMEM; + /* Check Oscillator Stop flag */ error =3D bq32k_read(dev, ®, BQ32K_SECONDS, 1); if (!error && (reg & BQ32K_STOP)) { @@ -280,10 +299,13 @@ static int bq32k_probe(struct i2c_client *client) if (client->dev.of_node) trickle_charger_of_init(dev, client->dev.of_node); =20 - rtc =3D devm_rtc_device_register(&client->dev, bq32k_driver.driver.name, - &bq32k_rtc_ops, THIS_MODULE); - if (IS_ERR(rtc)) - return PTR_ERR(rtc); + bq32k->rtc =3D devm_rtc_device_register(&client->dev, bq32k_driver.driver= .name, + &bq32k_rtc_ops, THIS_MODULE); + if (IS_ERR(bq32k->rtc)) + return PTR_ERR(bq32k->rtc); + + device_property_read_u32(dev, "ti,read-settle-us", &settle_us); + bq32k->read_delay_us =3D settle_us; =20 error =3D bq32k_sysfs_register(&client->dev); if (error) { @@ -293,7 +315,7 @@ static int bq32k_probe(struct i2c_client *client) } =20 =20 - i2c_set_clientdata(client, rtc); + i2c_set_clientdata(client, bq32k); =20 return 0; } --=20 2.51.0