Re: [PATCH v12 10/11] docs: iio: add documentation for adf41513 driver

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The documentation example for 'High Resolution Frequency Control' contains an inconsistency that actively misleads users about achieving sub-Hz precision.
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commit b24787f890c3b4daf22d09c32612a52b6731f5a4
Author: Rodrigo Alencar <rodrigo.alencar@analog.com>

docs: iio: add documentation for adf41513 driver

This commit adds documentation for the ADF41513 driver, describing the
supported devices, operating modes, and providing usage examples for
frequency control and monitoring.

> diff --git a/Documentation/iio/adf41513.rst b/Documentation/iio/adf41513.rst
> new file mode 100644
> --- /dev/null
> +++ b/Documentation/iio/adf41513.rst

[ ... ]

> +4.2 High Resolution Frequency Control
> +-------------------------------------
> +
> +Configure for sub-Hz resolution and set a precise frequency:
> +
> +.. code-block:: bash
> +
> +    # Set resolution to 0.1 Hz (100,000 µHz)
> +    root:/sys/bus/iio/devices/iio:device0> echo 0.1 > out_altvoltage0_frequency_resolution
> +
> +    # Set frequency to 12.102 GHz (1 µHz precision)
> +    root:/sys/bus/iio/devices/iio:device0> echo 12102000000 > out_altvoltage0_frequency
> +    root:/sys/bus/iio/devices/iio:device0> cat out_altvoltage0_frequency
> +    12101999999.980131

This isn't a code bug, but does this example contain an inconsistency that
could mislead users about achieving true sub-Hz precision?

The narrative claims to demonstrate 1 µHz precision, but it configures the
resolution to 0.1 Hz. As a result, the readback value shown
(12101999999.980131) misses the 12.102 GHz target by 0.019869 Hz (19,869 µHz).

This discrepancy shows the driver correctly satisfied the requested 0.1 Hz
(100,000 µHz) tolerance, likely by falling back to the lower-resolution 25-bit
fixed modulus mode rather than switching to the 49-bit variable modulus mode.

To actually achieve the advertised 1 µHz precision in the example, shouldn't
the resolution be set to a much smaller value, such as 0.000001?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260510-adf41513-iio-driver-v12-0-34af2ed2779f@analog.com?part=10