Re: [PATCH 2/3] dt-bindings: iio: temperature: ltc2983: support more parts

Krzysztof Kozlowski
2022-10-17T23:27:12Z

On 17/10/2022 02:53, Cosmin Tanislav wrote:
>
>
> On 10/17/22 04:59, Krzysztof Kozlowski wrote:
>> On 14/10/2022 08:37, Cosmin Tanislav wrote:
>>> From: Cosmin Tanislav <cosmin.tanislav@analog.com>
>>>
>>> Add support for the following parts:
>>> * LTC2984
>>> * LTC2986
>>> * LTM2985
>>>
>>> The LTC2984 is a variant of the LTC2983 with EEPROM.
>>> The LTC2986 is a variant of the LTC2983 with only 10 channels,
>>> EEPROM and support for active analog temperature sensors.
>>> The LTM2985 is software-compatible with the LTC2986.
>>>
>>> Signed-off-by: Cosmin Tanislav <cosmin.tanislav@analog.com>
>>> ---
>>> .../bindings/iio/temperature/adi,ltc2983.yaml | 63 +++++++++++++++++--
>>> 1 file changed, 59 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml b/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml
>>> index 722781aa4697..c33ab524fb64 100644
>>> --- a/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml
>>> +++ b/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml
>>> @@ -4,19 +4,27 @@
>>> $id: http://devicetree.org/schemas/iio/temperature/adi,ltc2983.yaml#
>>> $schema: http://devicetree.org/meta-schemas/core.yaml#
>>>
>>> -title: Analog Devices LTC2983 Multi-sensor Temperature system
>>> +title: Analog Devices LTC2983, LTC2986, LTM2985 Multi-sensor Temperature system
>>>
>>> maintainers:
>>> - Nuno Sá <nuno.sa@analog.com>
>>>
>>> description: |
>>> - Analog Devices LTC2983 Multi-Sensor Digital Temperature Measurement System
>>> + Analog Devices LTC2983, LTC2984, LTC2986, LTM2985 Multi-Sensor Digital
>>> + Temperature Measurement Systems
>>> +
>>> https://www.analog.com/media/en/technical-documentation/data-sheets/2983fc.pdf
>>> + https://www.analog.com/media/en/technical-documentation/data-sheets/2984fb.pdf
>>> + https://www.analog.com/media/en/technical-documentation/data-sheets/29861fa.pdf
>>> + https://www.analog.com/media/en/technical-documentation/data-sheets/ltm2985.pdf
>>>
>>> properties:
>>> compatible:
>>> enum:
>>> - adi,ltc2983
>>> + - adi,ltc2984
>>> + - adi,ltc2986
>>> + - adi,ltm2985
>>>
>>> reg:
>>> maxItems: 1
>>> @@ -26,7 +34,7 @@ properties:
>>>
>>> adi,mux-delay-config-us:
>>> description:
>>> - The LTC2983 performs 2 or 3 internal conversion cycles per temperature
>>> + The device performs 2 or 3 internal conversion cycles per temperature
>>> result. Each conversion cycle is performed with different excitation and
>>> input multiplexer configurations. Prior to each conversion, these
>>> excitation circuits and input switch configurations are changed and an
>>> @@ -145,7 +153,7 @@ patternProperties:
>>> adi,three-conversion-cycles:
>>> description:
>>> Boolean property which set's three conversion cycles removing
>>> - parasitic resistance effects between the LTC2983 and the diode.
>>> + parasitic resistance effects between the device and the diode.
>>> type: boolean
>>>
>>> adi,average-on:
>>> @@ -353,6 +361,41 @@ patternProperties:
>>> description: Boolean property which set's the adc as single-ended.
>>> type: boolean
>>>
>>> + "^temp@":
>>
>> There is already a property for thermocouple. Isn't a thermocouple a
>> temperature sensor? IOW, why new property is needed?
>>
> This node is needed for active analog temperature sensors.
> It has fewer options than the thermocouple, as it only supports
> a table to map from voltage to temperature and specifying whether
> the measurement is differential or single-ended.
>
> If you did as much as glimpsed at the datasheet you would have
> understood.

We receive a lot of bindings to review. If I glimpse through every
datasheet, when would I work?

Instead of expecting reviewer to dive into datasheets for this one
particular sensor, make it explicit in commit msg.

>
>>> + type: object
>>> + description:
>>> + Represents a channel which is being used as an active analog temperature
>>> + sensor.
>>> +
>>> + properties:
>>> + adi,sensor-type:
>>> + description:
>>> + Identifies the sensor as an active analog temperature sensor.
>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>> + const: 31
>>> +
>>> + adi,single-ended:
>>> + description: Boolean property which sets the sensor as single-ended.
>>
>> Drop "Boolean property which sets" - it's obvious from the type.
>>
>
> That's how the rest of the file is written.

Not really an argument... You can correct the other pieces in separate
patch.

>
>>
>>
>>> + type: boolean
>>> +
>>> + adi,custom-temp:
>>> + description:
>>> + This is a table, where each entry should be a pair of
>>
>> "This is a table" - obvious from the type.
>>
>
> That's how the rest of the file is written.
>
>>> + voltage(mv)-temperature(K). The entries must be given in nv and uK
>>
>> mv-K or nv-uK? Confusing...
>
> That's how the rest of the file is written.

The same.

>
> The chip uses mv-K, but the binding specifies nv-uK, the driver
> translates it into the appropriate unit.

It does not matter here, what the driver is doing. Use only one unit
here, matching the DTS.

>
>>
>>> + so that, the original values must be multiplied by 1000000. For
>>> + more details look at table 71 and 72.
>>
>> There is no table 71 in the bindings... It seems you pasted it from
>> somewhere.
>>
>
> It's pretty obvious that "Table" in a binding refers to the datasheet.

There are multiple datasheets and how would I know to which one this refers?

> But if you meant datasheet, not binding, you're looking at the wrong
> datasheet then.
> Also, that's how the rest of the file is written.

Not really an argument... Poor examples like to spread, it's an effort
to drop them.

>
>>> + Note should be signed, but dtc doesn't currently maintain the
>>> + sign.
>>
>> What do you mean? "Maintain" as allow or keep when building FDT? What's
>> the problem of using negative numbers here and why it should be part of
>> bindings?
>>
>
> You're really clueless, I'll let you figure it out on your own.

Yes, I am clueless and that's not the way how the review conversation
should look like.

NAK.

> Also, that's how the rest of the file is written.
>
>>> + $ref: /schemas/types.yaml#/definitions/uint64-matrix
>>> + minItems: 3
>>> + maxItems: 64
>>> + items:
>>> + minItems: 2
>>> + maxItems: 2
>>
>> Instead describe the items with "description" (and maybe constraints)
>> like here:
>>
>> https://elixir.bootlin.com/linux/v5.19/source/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml#L278
>>
>
> That's how the rest of the file is written.
> If you really want to use something different, you can submit a
> patch later and fix the whole binding however you want.

Nope. I expect the new pieces to be correct, not incorrect because
"there is already poor pattern, so I will do the same".

If inconsistency bothers you, anyone can fix it in following up patch.
Also you.

Best regards,
Krzysztof