linux-kernel - Re: [PATCH 3/3] arm64: dts: qcom: sm7225-fp4: Revert "arm64: dts: qcom: sm7225-fairphone-fp4: Add AW8695 haptics"

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Message-ID: <7859abb1-ae99-d33f-a8fc-c76304057df9@linaro.org>
Date:   Mon, 28 Aug 2023 09:00:21 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Luca Weiss <luca.weiss@...rphone.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] arm64: dts: qcom: sm7225-fp4: Revert "arm64: dts:
 qcom: sm7225-fairphone-fp4: Add AW8695 haptics"

On 28/08/2023 08:56, Luca Weiss wrote:
> Hi Krzysztof,
> 
> On Sun Aug 27, 2023 at 2:28 PM CEST, Krzysztof Kozlowski wrote:
>> This reverts commit 413821b7777d062b57f8dc66ab088ed390cbc3ec because it
>> was never reviewed, was buggy (report from kernel test robot:
>> https://lore.kernel.org/all/202204090333.QZXMI2tu-lkp@intel.com/) and
> 
> (I wouldn't say this part is accurate, the robot just didn't use a tree
> with the i2c10 node already present, it was sent in an earlier patch
> IIRC, but whatever)
> 
>> used undocumented, broken bindings.  Half of the properties in this
>> device are questioned, thus adding DTS node causes only errors and does
>> not make the device usable without the bindings and driver part:
>>
>>   sm7225-fairphone-fp4.dtb: haptics@5a: failed to match any schema with compatible: ['awinic,aw8695']
>>   sm7225-fairphone-fp4.dtb: haptics@5a: awinic,tset: b'\x12' is not of type 'object', 'array', 'boolean', 'null'
>>   sm7225-fairphone-fp4.dtb: haptics@5a: awinic,r-spare: b'h' is not of type 'object', 'array', 'boolean', 'null'
>>
>> Since bindings were abandoned (4 months since review), revert the commit
>> to avoid false sense of supporting something which is not supported.
> 
> I've been avoiding touching this topic again since I'm really not sure
> how to resolve.

Happens, but the DTS should not have been applied in such case.

> 
> There's a bunch of magic registers being written to in the downstream
> driver, I don't have any documentation for that so I'm not exactly sure
> what I can do to make nice bindings with proper properties.
> 
> Would you recommend just hardcoding some of these properties in the
> driver, assuming they're constant for every AW8695, even though the
> downstream driver has these properties in devicetree? Because of that I
> assumed these properties could differ per implementation / usage of the
> AW8695 in different devices.

Yes, keep them in the driver.

Best regards,
Krzysztof