Re: [PATCH v3 2/3] iio: pressure: Add driver for Sensirion SDP500

Krzysztof Kozlowski
2024-07-04T09:49:27Z

On 04/07/2024 09:49, Petar Stoykov wrote:
> On Tue, Jul 2, 2024 at 5:17 PM Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>>
>> On 02/07/2024 16:59, Petar Stoykov via B4 Relay wrote:
>>> From: Petar Stoykov <pd.pstoykov@gmail.com>
>>>
>>> Sensirion SDP500 is a digital differential pressure sensor. The sensor is
>>> accessed over I2C.
>>>
>>
>> ...
>>
>>> +
>>> +static const struct of_device_id sdp500_of_match[] = {
>>> + { .compatible = "sensirion,sdp500" },
>>> + { .compatible = "sensirion,sdp510" },
>>
>> Devices look compatible, so express it in the bindings with fallback to
>> sdp500 (oneOf, see example-schema).
>
> Hi Krzysztof,
> I tried to understand the explanation in the example-schema. I must say it is
> a bit confusing, but I can't offer improvement because I'm not sure I
> understand it fully yet.
> Can you verify if this is what you expect the bindings file to read?
> properties:
> compatible:
> oneOf:
> - items:
> - const: sensirion,sdp510
> - const: sensirion,sdp500
> - items:
> - const: sensirion,sdp500

Almost.

oneOf:
- items:
- const: sensirion,sdp510
- const: sensirion,sdp500
- const: sensirion,sdp500

>
> So the device tree should have either this
> compatible = "sensirion,sdp510", "sensirion,sdp500"
> Or
> compatible = "sensirion,sdp500"
> The first would mean that 510 falls back to 500, right?

Yes

>
> From what I've seen it is rare to have two strings in "compatible" so I didn't

Rare? It's everywhere in SoC and in many places for standalone
devices/hardware.

> know of this mechanism of "fallback" in the dts. I expected to just write the
> name of my device (let's say "sensirion,sdp510") and the driver would handle it.
> But I'm learning. Expectations change.

Best regards,
Krzysztof