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Mon, 02 Mar 2026 05:06:57 -0800 (PST) From: Archit Anant To: jic23@kernel.org, lars@metafoo.de, Michael.Hennerich@analog.com Cc: dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Archit Anant Subject: [PATCH v3 2/4] iio: adc: ad799x: cache regulator voltages during probe Date: Mon, 2 Mar 2026 18:36:30 +0530 Message-Id: <20260302130632.29144-3-architanant5@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260302130632.29144-1-architanant5@gmail.com> References: <20260302130632.29144-1-architanant5@gmail.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" Reading the regulator voltage via regulator_get_voltage() can be a slow operation. Since the reference voltages for this ADC are not expected to change at runtime, it is inefficient to query the regulator API every time userspace reads the IIO_CHAN_INFO_SCALE attribute. Cache the VCC and VREF voltages in the state structure during probe(). This improves the performance of ad799x_read_raw() and removes the dependency on the regulator pointers during fast-path reads. Suggested-by: Jonathan Cameron Signed-off-by: Archit Anant --- drivers/iio/adc/ad799x.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c index 7775be874081..35e0589428d0 100644 --- a/drivers/iio/adc/ad799x.c +++ b/drivers/iio/adc/ad799x.c @@ -135,6 +135,10 @@ struct ad799x_state { u16 config; =20 unsigned int transfer_size; + + int vcc_uv; + int vref_uv; + IIO_DECLARE_DMA_BUFFER_WITH_TS(__be16, rx_buf, AD799X_MAX_CHANNELS); }; =20 @@ -303,9 +307,9 @@ static int ad799x_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: if (st->vref) - ret =3D regulator_get_voltage(st->vref); + ret =3D st->vref_uv; else - ret =3D regulator_get_voltage(st->reg); + ret =3D st->vcc_uv; =20 if (ret < 0) return ret; @@ -809,6 +813,10 @@ static int ad799x_probe(struct i2c_client *client) ret =3D regulator_enable(st->reg); if (ret) return ret; + ret =3D regulator_get_voltage(st->reg); + if (ret < 0) + goto error_disable_reg; + st->vcc_uv =3D ret; =20 /* check if an external reference is supplied */ if (chip_info->has_vref) { @@ -827,6 +835,11 @@ static int ad799x_probe(struct i2c_client *client) ret =3D regulator_enable(st->vref); if (ret) goto error_disable_reg; + + ret =3D regulator_get_voltage(st->vref); + if (ret < 0) + goto error_disable_vref; + st->vref_uv =3D ret; } } =20 --=20 2.39.5