Re: [PATCH v6 4/4] iio: flow: add Sensirion SLF3S liquid flow sensor driver

[David Lechner <dlechner@baylibre.com>]

On 7/28/26 4:49 PM, Wadim Mueller wrote:
> Add a driver for the Sensirion SLF3S family of digital
> liquid-flow sensors on I2C.  Currently supported variants are
> SLF3S-0600F, SLF3S-1300F and SLF3S-4000B; they share the same
> register map and differ only in flow-scale factor and calibrated
> measurement range.  The variant (and therefore the scale) is
> auto-detected from the product-information register at probe time;
> a sensor reporting an unknown sub-type falls back to the variant
> named in the device tree / I2C table, so a drop-in replacement part
> keeps working on a kernel that does not know its sub-type yet.
> 

...

> +static bool slf3s_crc_valid(const struct slf3s_data *sf, const u8 *block)
> +{
> +	return crc8(sf->crc_table, block, 2, SLF3S_CRC8_INIT) == block[2];
> +}
> +
> +/*
> + * Read the product-info block and pick the matching variant.  The
> + * sub-type byte returned by the sensor is the source of truth; a
> + * DT-supplied compatible only seeds an initial guess and is overridden
> + * on mismatch (with an informational message so misconfigured device
> + * trees are easy to spot).

In the past, Jonathan has always argued that the devicetree should be
trusted more than what the device self-reports. This seems a departure
from that. Why are we making an exception here?

We have to trust that the devicetree is correct for everything else
that can't self-detect anyway.