Re: [PATCH 4/4] iio: resolver: add new driver for AD2S1210

[Rob Herring <robh@kernel.org>]

On Wed, Sep 20, 2023 at 12:02:53PM -0500, David Lechner wrote:
> This adds a new driver for Analog Devices, Inc. AD2S1210 resolver to
> digital converter. The driver is based on the staging driver with the
> following improvements:
> 
> Fixes:
> - Fix use before initialization bug in probe.
> - Fix not checking error returns in probe.
> - Remove spi_setup() and spi_set_drvdata() from probe.
> - Fix ordering of devm_iio_device_register()
> - Remove incorrect hysteresis logic
> 
> Changes:
> - Use BIT/GENMASK macros.
> - Use devicetree to get CLKIN frequency (was sysfs attribute).
> - No longer bit-shift the raw value for IIO_CHAN_INFO_RAW.
> - Use regmap for register access.
> - Remove config sysfs attribute.
> - Use gpio array for mode and resolution gpios.
> - Invert sample gpio logic and use GPIO_ACTIVE_LOW in devicetree.
> - Change hysteresis to use IIO_CHAN_INFO_HYSTERESIS instead of custom
>   device attribute.
> - Rename fexcit attribute to excitation_frequency.
> - Use devicetree to specify resolution instead of sysfs attribute.

Why? sysfs allows a user to change at run-time. DT is a firmware 
change. What/who determines the resolution? Unless it's the hardware 
design/designer, it probably doesn't belong in DT.

Rob