Re: [PATCH v6 1/6] dt-bindings: iio: imu: icm42600: Add ICM-42670-P

[Jean-Baptiste Maneyrol]

>________________________________________
>From: Marcelo Schmitt <marcelo.schmitt1@xxxxxxxxx>
>Sent: Tuesday, October 13, 2026 00:03
>To: Krzysztof Kozlowski
>Cc: Kanak Shilledar; andy@xxxxxxxxxx; robh@xxxxxxxxxx; Kernel; macromorgan@xxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; conor+dt@xxxxxxxxxx; joshua.crofts1@xxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; Jean-Baptiste Maneyrol; dlechner@xxxxxxxxxxxx; nuno.sa@xxxxxxxxxx; krzk+dt@xxxxxxxxxx; jic23@xxxxxxxxxx; Henrik Grimler; linux-iio@xxxxxxxxxxxxxxx
>Subject: Re: [PATCH v6 1/6] dt-bindings: iio: imu: icm42600: Add ICM-42670-P
>
>Hi Krzysztof, On 10/12, Krzysztof Kozlowski wrote: > On 12/10/2026 12: 43, Kanak Shilledar wrote: > > Hi Krzystztof, > > > > On Mon, 2026-10-12 at 10: 58 +0200, Krzysztof Kozlowski wrote: > >> On Fri, Oct 09, 2026
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>Hi Krzysztof,
>
>On 10/12, Krzysztof Kozlowski wrote:
>> On 12/10/2026 12:43, Kanak Shilledar wrote:
>> > Hi Krzystztof,
>> >
>> > On Mon, 2026-10-12 at 10:58 +0200, Krzysztof Kozlowski wrote:
>> >> On Fri, Oct 09, 2026 at 04:12:06PM +0200, Kanak Shilledar wrote:
>> >>>    It has a configurable host interface that supports I3C, I2C and
>> >>> SPI serial
>> >>> -  communication, features a 2kB FIFO and 2 programmable interrupts
>> >>> with
>> >>> +  communication, features up to 2.25kB FIFO and 2 programmable
>> >>> interrupts with
>> >>>    ultra-low-power wake-on-motion support to minimize system power
>> >>> consumption.
>> >>>
>> >>>    Other industry-leading features include InvenSense on-chip APEX
>> >>> Motion
>> >>> @@ -28,6 +29,7 @@ properties:
>> >>>    compatible:
>> >>>      oneOf:
>> >>>        - enum:
>> >>> +          - invensense,icm42370p
>> >>>            - invensense,icm42600
>> >>>            - invensense,icm42602
>> >>>            - invensense,icm42605
>> >>
>> >> Why aren't the interrupts required?
>> >
>> > The interrupts are only required if using the device is used in
>> > buffered mode. Which will be added later and the dt-binding will be
>> > updated when the buffer support is added. Currently, the device works
>> > without any interrupts.
>> >
>>
>> That's misleading or confusing. Either the device works or does not
>> without interrupt hooked up. Consult hardware datasheet if in doubts.
>>
>> Driver support is different thing here and you cannot make it required
>> later, because that would be unjustified ABI break.
>
>I looked into icm42605 data sheet and saw no clear statement about the interrupts
>being required. The timing diagrams only show protocol specific lines and it
>looks like the interrupt sources can even be disabled (not routed out to any
>interrupt pin). Maybe I'm missing something and the interrupts are required for
>some sort of reset function or so? Otherwise, I don't see how the interrupts are
>required.
>
>Kanak, do you have access to any of those other chips to test whether they work
>without interrupts? If possible, can you also check the data sheets for the other
>parts besides icm42370p and icm42605?
>
>Maybe
>  - if:
>      properties:
>        compatible:
>          contains:
>            enum:
>              - invensense,icm42600
>              - invensense,icm42602
>              - invensense,icm42605
>              - invensense,icm42622
>              - invensense,icm42631
>              - invensense,icm42686
>              - invensense,icm42688
>    then:
>      required:
>        - interrupts
>was a documentation mistake?
>
>With best regards,
>Marcelo
>
>

Hello,

I can confirm that all icm426xx chips can work without interrupt by just polling
the data.

Interrupts were declared as required at the time only because the driver doesn't
work without interrupt (probe will fails).

Hardware speaking only, this is indeed a documentation mistake.

Thanks,
JB