From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dl1-f53.google.com (mail-dl1-f53.google.com [74.125.82.53]) (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 671033DE452 for ; Thu, 16 Apr 2026 14:21:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776349317; cv=none; b=Qf7+DlvrsQ0lJgGwFFflk1qXjc6lnhf10BqLqj8CP4Oo7+ddX+I6xuqsaccAjRBuWDQjJcVGGoDpQ0Vtcs7EF5ArR7ogVdTISiwpTG7dDuDRqWKSAMisKMyfh/LTF6mMO+9lCD0cZCA9jyl00AUBw5om3GOStwHq4fvIo5diINk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776349317; c=relaxed/simple; bh=mAjT45WQhnjtVyYVvBf2pQ/QyrbZdt2tiyZOsc7r+ck=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=CkTK+G7+jsMqkOuAxsalxAmwGlQ5Uv5xRYPqfB6ilKJlBhL1H0ADuCS+LXyUdJVgjdQDfa/pszuXIOPBlEpo9ZoN00QWd1M9lp4r0BS352/kEsKGV2BtAznCX4rbdFoERMSBtQmcKJ3F8tbcbZw+Fk8N8M1iH6kB1Z7JjWDPSvo= 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=MeYkFXFz; arc=none smtp.client-ip=74.125.82.53 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="MeYkFXFz" Received: by mail-dl1-f53.google.com with SMTP id a92af1059eb24-12711867ca1so724359c88.3 for ; Thu, 16 Apr 2026 07:21:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; t=1776349316; x=1776954116; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=uFu1DzNio6n1RumPdBhDerBBGIlEwFQJz0L3Q0gtmOw=; b=MeYkFXFzjahrrawyt3Wj8LV9F13419NKFXYxp7KELlqqAIViWf80rbMZRtl0pQ2tTA omYiOW4Uto5VpDELQPgEnVAlQnniweLcW9wE8bD0dtZ0mtbz7+HFy0nZhkwPp+LBr8Vj hi21UVyqnddWeKjExdxOMKLcV/wRSzZGgbAy5SlX0dTqtl51RpMHi7lc513Cn6rDkpfE whdpkk3VaopkKGaSV1HLygQB8bcKAu6OgRCLwJytYjLtUleP0a0roU53HJffnCWqBbBy WrEK2L/rmJdw8WI8kgGUickkw3DLs8ZlI+Dx9cjilXKRGxrk9nZV2TLkS7OLmMsB8BIr baJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776349316; x=1776954116; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=uFu1DzNio6n1RumPdBhDerBBGIlEwFQJz0L3Q0gtmOw=; b=YG1EUE/0we9fRA5T0oHBaTk1CdKskekrNVC4X0nFsStpC+yj7FSmjjPBEGFP/OY/GW AkUejm4d9+rNuNeMufRNNG+cyXEyDKb+mXrf7+0f++ak72NytKJOt7FDIGiLcRiRhKI1 dyraFRGFvfGJjNTswZtlQsW6FvfLGlqBRDPgFWEKP3lVVDWCXu7TVel+eEIL/6dHNhxb dHp5W167BbTi6d+FQMm6EaT5uzB80tZWFpP7qDtErGqCxMK9NCFD2rQ93lXVaL+79iH9 qzFMT7fH8hJYOolkxAz3WH9aBfX7fS689lC+5JTXwUXiQMZ5cqUNugOcdTwJ1EoKcVT3 PxQg== X-Gm-Message-State: AOJu0YwoxkVqO7akeoNdXazDiBM658xDmeeGBuAZdIwJZ3TOhC5IRCdU 373OnPNoBo+Y6Xan4EWnQ4CABfkJBeoNQ/6zz2yk3FLjYfO3dugip9a4BB0DF+lPag== X-Gm-Gg: AeBDieuDsJ1CWPM7VjSd/E4WPLGllcSLCeTsutVJCnCprCiwrq1NxvTOCFe6Llj5e8I EoWtfrWqb8Q83F0J7dhuBPH+dmIzbgZ7EAxlmvk2NOQiwOSxk2QiR8w8ycsoDnpW7N97J2mNa05 evbn6N6n3zWb3O7ecOLKEVghZZsKFYIHM7KKK9fULPR61MU02mdJxVMSrva4uWsoezdL+2xnD82 SL3uzbI/sHAl+yHnP7nEcd5dhg4iyH4QQY1+bZZ2P45FlBEPhiR4rbot/uVwnt/eKjDkss6w88P 69DTnfAynGUI21jQFUCTkYXNGUzQM6zZRLTEJDlw7maOx9gGZMYQHAJiDyKxmffmYErvh3d2zTg F7XvtMId7eNH5OyvgC+o/MsH8Snsn0PbpCW9xXHnKKEPMAYoOSujtW40StOlOnfGqrfhZ+sPxst lVN4uxigZHnL4qw0c/M6T3v4d6Ih+iy+1u0nf6hkYeKAZRi7Vnf2bY4oczm/8= X-Received: by 2002:a05:7300:7495:b0:2c1:7ca:cec2 with SMTP id 5a478bee46e88-2e193539dd3mr726559eec.8.1776349315133; Thu, 16 Apr 2026 07:21:55 -0700 (PDT) Received: from adriana-schoodic-rtc.sjc.aristanetworks.com ([74.123.28.13]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2de8c605851sm7577478eec.9.2026.04.16.07.21.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2026 07:21:54 -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 v3] rtc: bq32000: add configurable delay between RTC reads Date: Thu, 16 Apr 2026 07:21:51 -0700 Message-ID: <20260416142151.3385827-1-adriana@arista.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 delay before reading the RTC registers in order to provide a sufficient idle time for the hardware to sync with the register buffer. Signed-off-by: Adriana Stancu --- drivers/rtc/rtc-bq32k.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c index 7ad34539be4d..edce95eb328f 100644 --- a/drivers/rtc/rtc-bq32k.c +++ b/drivers/rtc/rtc-bq32k.c @@ -16,6 +16,7 @@ #include #include #include +#include #define BQ32K_SECONDS 0x00 /* Seconds register address */ #define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */ @@ -89,9 +90,17 @@ static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len) static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm) { + struct i2c_client *client = to_i2c_client(dev); struct bq32k_regs regs; int error; + /* + * When the device doesn't have the interrupt connected, prevent + * userpace from polling the RTC registers to frequently. + */ + if (client->irq <= 0) + usleep_range(2000, 2500); + error = bq32k_read(dev, ®s, 0, sizeof(regs)); if (error) return error; -- 2.51.0