From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f47.google.com (mail-pj1-f47.google.com [209.85.216.47]) (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 2F6D4395247 for ; Sun, 8 Mar 2026 18:29:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772994559; cv=none; b=T2hDzETJXvVICGKAfXtYff5lm0+dJ2/pj9C4Nr7Wl7/VgZD4J/6HjskXNb8G4LXDVLTyinwsDRhN0r6bpE/HbrtlFVfYBjUMx/ibAqM+IG0sH8kdkZhGN1O3Zeq/BESf1VwayvNOBZobo/x2nVcN+kmYa/C+RCvOJyqqgJN4QIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772994559; c=relaxed/simple; bh=x5Is6TuJfxAgrtFz4XT+C5a3nBwqtfBUhZaPk0bie0Y=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=YTIABdZZZS3XIHWl5ZEczqP61LZtt20XyZ7QxVZ7nWdccwPG90sNoJsiXV+RzBv9q7T8hoLegBhzC46nQJn67EPIyKG5pl/bV5Yixnq9p5pEHk5Ykeyta2dXOgmGP5ONasSA1GmiGTJobKpL61qSqnPpAJSL4JK6XCDtf034uOw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=SBg0nUTa; arc=none smtp.client-ip=209.85.216.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="SBg0nUTa" Received: by mail-pj1-f47.google.com with SMTP id 98e67ed59e1d1-358e3cc5e7eso5151778a91.0 for ; Sun, 08 Mar 2026 11:29:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1772994557; x=1773599357; 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=5REngnkmAV3py6hSuWlfdMiQRrfGu2JrLts1i1aI7wE=; b=SBg0nUTa4HB4f7srpxNPlEnoxeEzwNulgV0F4XUC91XY/Cc8jOVG7u42GEnHFu1Fhl MNwxuicQqyd0O5BW0qJ0EZMl0a53hv7Kl/CQq1vH6BuUaHUDkEY6ROnsg0tvKHEyUJX+ 5K4q3AlXCuFesLJLW2eZTBXvZwrUDBvplzHp9GZndTkcyKKje9bSrZgEqmhu1KToK216 F+0F7sQqB/us6Wo7MwMd9jbGOoO2N2DW5e3Ecr6HrwcGVMGUYUHMKbXi8KLLoOl6NHZB XkgnK67lo553GKSv+BnXBJkkJKW/qhmIPS9qddUzqcBCOQIya+yckU9lexVzwrw9raUH FuCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772994557; x=1773599357; 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=5REngnkmAV3py6hSuWlfdMiQRrfGu2JrLts1i1aI7wE=; b=tPBwoxFe4rGGmY8DlP6tPo4KUj/Yrf/wR27aslJ64bmx3LBaqS9lg2LhfXAe8YM556 I0xbz18ZqaHzk32Z43vvB0DJrnt4v7JjFhJ17uf0FNSrLrEY3snxfbfA8wxncWVRbwtL PXpOvj14D0lgv5aI3enQgJcXXUvkI0Po00KYajs0/O1RmLzEOSnvPQYTQG/jlaNM8Ey7 l3d/Iu9c7v75dss6B0/TFpkUcdxrVD3H6+FUpr8y/5U40lp3Fpm+ClW9uWMzCUs73+xr a4OP00Ncj024wtHxkI2OgN0f9KM53XgYsksrsQQh/KHV4IrA/ELe/fD4e6dGaEwQtwHl B9yA== X-Forwarded-Encrypted: i=1; AJvYcCV9X+G0lgZ6a0nY/yrfN9JD/BcoCVjOtMwht/PA9RSjPGUR06oxllvQrw9+SQimxFEBbkQEGPnkYmA=@vger.kernel.org X-Gm-Message-State: AOJu0Yzc55N3pNrIx3l1iCyaRdm5GAgrwVNoWfgJlXx78E6PedSJzd69 qOZtWd0F4LsQMec1qMx3Snm340ynRTsk8el8aAn9TjUjRbV/PaUf5WZJ X-Gm-Gg: ATEYQzzTrvRtdaKq1vd4aNw89L3gp/ASn23sVTVG9pXe1IOWW5KpP1Ve47jWHc/UtzO 3iAk/VxED1xK1DTj8ua+kzHNtpjekYUV0MoKoSP+sQOd/KVuxUqqXCZyE2hM35+BmhqGAPvRRFs s+c8ioyxkZBTsZkGI6v6xgSyW0HExLtFW9U72s2Y14RMpa5oVdpRiIRr1Sh8LZzpKSVi6dntcQT M6VcnHwT74H7kH+lZykUGM8kOY1kLQmDRweHOnFQxNG/PhYpDvTmfT+o+akdeDiWygRKCEeug4v BLTv0jTNLqnrZ256JrWVVpRv+z75EGsGzQ9PZQtqVEIPspgZuDPcZ+3AthjjE+CTtGAZq4E5ptm LUZo/Nk76lWldTc3OxPW/5eC03Be6tcgELZvKRYx8ywJ+ij02JAHFrlJ2+dB3aeSb/bQKa7Z5Xi W4/UxVT13kSHngeyM+iPn5/CikfY6egmRGpEHqmR+Ll84SsPTvl2M= X-Received: by 2002:a17:902:f54e:b0:29e:9387:f2b0 with SMTP id d9443c01a7336-2ae824fcc81mr93036945ad.39.1772994557514; Sun, 08 Mar 2026 11:29:17 -0700 (PDT) Received: from debian.ari ([152.58.179.53]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ae83f783dbsm89006965ad.42.2026.03.08.11.29.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Mar 2026 11:29:17 -0700 (PDT) From: Archit Anant To: jic23@kernel.org, dlechner@baylibre.com Cc: lars@metafoo.de, Michael.Hennerich@analog.com, nuno.sa@analog.com, andy@kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Archit Anant Subject: [PATCH v4 2/4] iio: adc: ad799x: cache regulator voltage during probe Date: Sun, 8 Mar 2026 23:58:09 +0530 Message-Id: <20260308182811.33471-3-architanant5@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260308182811.33471-1-architanant5@gmail.com> References: <20260308182811.33471-1-architanant5@gmail.com> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Reading the regulator voltage via regulator_get_voltage() can be a slow operation. Since the reference voltage for this ADC is not expected to change at runtime, it is inefficient to query the regulator API every time userspace reads the IIO_CHAN_INFO_SCALE attribute. Determine the active reference voltage (either VREF or VCC) during probe() and cache it in a single variable in the state structure. This improves the performance of ad799x_read_raw(), removes the dependency on the regulator pointers during fast-path reads, and allows the removal of a redundant negative-value check. Suggested-by: Jonathan Cameron Suggested-by: David Lechner Signed-off-by: Archit Anant --- drivers/iio/adc/ad799x.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c index c1a7fa37706f..28f1901698a6 100644 --- a/drivers/iio/adc/ad799x.c +++ b/drivers/iio/adc/ad799x.c @@ -135,6 +135,9 @@ struct ad799x_state { u16 config; unsigned int transfer_size; + + int vref_uV; + IIO_DECLARE_BUFFER_WITH_TS(__be16, rx_buf, AD799X_MAX_CHANNELS); }; @@ -302,14 +305,7 @@ static int ad799x_read_raw(struct iio_dev *indio_dev, GENMASK(chan->scan_type.realbits - 1, 0); return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: - if (st->vref) - ret = regulator_get_voltage(st->vref); - else - ret = regulator_get_voltage(st->reg); - - if (ret < 0) - return ret; - *val = ret / 1000; + *val = st->vref_uV / 1000; *val2 = chan->scan_type.realbits; return IIO_VAL_FRACTIONAL_LOG2; } @@ -809,6 +805,10 @@ static int ad799x_probe(struct i2c_client *client) ret = regulator_enable(st->reg); if (ret) return ret; + ret = regulator_get_voltage(st->reg); + if (ret < 0) + goto error_disable_reg; + st->vref_uV = ret; /* check if an external reference is supplied */ if (chip_info->has_vref) { @@ -827,6 +827,11 @@ static int ad799x_probe(struct i2c_client *client) ret = regulator_enable(st->vref); if (ret) goto error_disable_reg; + + ret = regulator_get_voltage(st->vref); + if (ret < 0) + goto error_disable_vref; + st->vref_uV = ret; } } -- 2.39.5