linux-kernel - Re: [PATCH 2/2] dt-bindings: iio: imu: mpu6050: Add icm20600 bindings to mpu6050

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Message-ID: <20230422181914.24810cc0@jic23-huawei>
Date:   Sat, 22 Apr 2023 18:19:14 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Hermes Zhang <chenhuiz@...s.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <robh+dt@...nel.org>,
        "Jean-Baptiste Maneyrol" <jmaneyrol@...ensense.com>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kernel@...s.com>, Lars-Peter Clausen <lars@...afoo.de>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH 2/2] dt-bindings: iio: imu: mpu6050: Add icm20600
 bindings to mpu6050

On Sat, 22 Apr 2023 14:14:49 +0800
Hermes Zhang <chenhuiz@...s.com> wrote:

> 在 2023/4/21 16:23, Krzysztof Kozlowski 写道:
> > Didn't we start switching to compatible groups of devices? This looks
> > compatible with 20602.  
> 
> Hi Krzysztof,
> 
> Sorry, I may not aware of this. Could you give some more info about the 
> compatible groups? Yes, the icm20602 is quite similar as icm20600.

If it's compatible enough that a device tree that lists
compatible = "invensense,icm20600", "invensense,icm20602"
would work correctly with an old kernel by first checking for invensense,icm20600
then falling back to invense,icm20602 then it should be listed with that fallback.

See the existing block that covers the fallback form icm20608d to icm20608

       - items:
          - const: invensense,icm20608d
          - const: invensense,icm20608

Note it is fine if the driver 'warns' that it's found a WHOAMI value it doesn't
know as long as it then goes on and works correctly.  Thus there can't be
any incompatibilities between the two parts when we consider the functionality the
driver implements today.  If we add features in future that aren't compatible, that's
fine because we will be matching against the more specific compatible you are
adding here.

Jonathan

> 
> Thanks & Best Regards,
> 
> Hermes
>