From: "Sabau, Radu bogdan" <Radu.Sabau@analog.com>
To: "David Lechner" <dlechner@baylibre.com>,
"Lars-Peter Clausen" <lars@metafoo.de>,
"Hennerich, Michael" <Michael.Hennerich@analog.com>,
"Jonathan Cameron" <jic23@kernel.org>,
"Sa, Nuno" <Nuno.Sa@analog.com>,
"Andy Shevchenko" <andy@kernel.org>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
"Conor Dooley" <conor+dt@kernel.org>,
"Uwe Kleine-König" <ukleinek@kernel.org>,
"Liam Girdwood" <lgirdwood@gmail.com>,
"Mark Brown" <broonie@kernel.org>,
"Linus Walleij" <linusw@kernel.org>,
"Bartosz Golaszewski" <brgl@kernel.org>,
"Philipp Zabel" <p.zabel@pengutronix.de>,
"Jonathan Corbet" <corbet@lwn.net>,
"Shuah Khan" <skhan@linuxfoundation.org>
Cc: "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pwm@vger.kernel.org" <linux-pwm@vger.kernel.org>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>
Subject: RE: [PATCH v6 3/4] iio: adc: ad4691: add triggered buffer support
Date: Mon, 6 Apr 2026 09:22:23 +0000 [thread overview]
Message-ID: <LV9PR03MB84143905DD2E10BAC2151EEFF75DA@LV9PR03MB8414.namprd03.prod.outlook.com> (raw)
In-Reply-To: <e38e5b97-e90f-4613-a15e-6c3d08cd77f7@baylibre.com>
> -----Original Message-----
> From: David Lechner <dlechner@baylibre.com>
> Sent: Saturday, April 4, 2026 6:12 PM
...
> > +
> > +/*
> > + * Valid ACC_DEPTH values where the effective divisor equals the count.
> > + * From Table 13: ACC_DEPTH = 2^N yields right-shift = N, divisor = 2^N.
> > + */
> > +static const int ad4691_oversampling_ratios[] = { 1, 2, 4, 8, 16, 32 };
>
> It would be nice to add oversampling in a separate commit as that is a
> separate feature.
Do you think this would be suitable after the offload commit?
>
> Oversampling also affects sampling frequency. When there isn't oversampling,
> sample rate == conversion rate. However, with oversampling, sample rate ==
> conversion rate / oversampling ratio (because each sample involves #OSR
> conversions).
>
> So more code will be required to make IIO_CHAN_INFO_SAMP_FREQ
> attributes
> (both read/write_raw and read_avail) adjust the values based on the current
> oversampling ratio.
I agree with this, the sampling frequency differs when oversampling is used.
Will add that in the next version.
>
> > +
> > static const struct ad4691_chip_info ad4691_chip_info = {
> > .channels = ad4691_channels,
...
> > +
> > + st->scan_msg.spi = spi;
>
> This isn't how the SPI framework is intended to be used. We should
> have st->spi = spi in probe instead.
You are right. The spi pointer was removed from struct in earlier versions
since the message wasn't pre-prepared back then, though now it is needed.
>
> > +
> > + ret = spi_optimize_message(spi, &st->scan_msg);
> > + if (ret) {
...
> > +};
> > +
> > +static irqreturn_t ad4691_irq(int irq, void *private)
> > +{
> > + struct iio_dev *indio_dev = private;
> > + struct ad4691_state *st = iio_priv(indio_dev);
> > +
> > + /*
> > + * GPx has asserted: stop conversions before reading so the
>
> Does this happen per-channel or only once per complete sequence?
>
This one happens per complete sequence.
next prev parent reply other threads:[~2026-04-06 9:22 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-03 11:03 [PATCH v6 0/4] iio: adc: ad4691: add driver for AD4691 multichannel SAR ADC family Radu Sabau via B4 Relay
2026-04-03 11:03 ` [PATCH v6 1/4] dt-bindings: iio: adc: add AD4691 family Radu Sabau via B4 Relay
2026-04-03 11:03 ` [PATCH v6 2/4] iio: adc: ad4691: add initial driver for " Radu Sabau via B4 Relay
2026-04-04 14:25 ` David Lechner
2026-04-03 11:03 ` [PATCH v6 3/4] iio: adc: ad4691: add triggered buffer support Radu Sabau via B4 Relay
2026-04-04 15:12 ` David Lechner
2026-04-05 8:57 ` Andy Shevchenko
2026-04-06 9:22 ` Sabau, Radu bogdan [this message]
2026-04-06 13:39 ` David Lechner
2026-04-03 11:03 ` [PATCH v6 4/4] iio: adc: ad4691: add SPI offload support Radu Sabau via B4 Relay
2026-04-04 15:34 ` David Lechner
2026-04-06 9:34 ` Sabau, Radu bogdan
2026-04-06 13:44 ` David Lechner
2026-04-06 14:16 ` Sabau, Radu bogdan
2026-04-06 15:02 ` David Lechner
2026-04-07 12:38 ` Sabau, Radu bogdan
2026-04-04 15:57 ` David Lechner
2026-04-06 10:39 ` Sabau, Radu bogdan
2026-04-06 11:08 ` Sabau, Radu bogdan
2026-04-06 13:30 ` Sabau, Radu bogdan
2026-04-06 13:56 ` David Lechner
2026-04-06 14:20 ` Sabau, Radu bogdan
2026-04-06 13:53 ` David Lechner
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