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Date:   Mon, 11 Apr 2022 17:11:04 +0200
Message-Id: <CJ7I91AXGGCE.24GR11X2CBJ2J@otso>
From:   "Luca Weiss" <luca.weiss@fairphone.com>
To:     "Krzysztof Kozlowski" <krzysztof.kozlowski@linaro.org>,
        <linux-input@vger.kernel.org>
Cc:     <~postmarketos/upstreaming@lists.sr.ht>,
        <phone-devel@vger.kernel.org>,
        "Dmitry Torokhov" <dmitry.torokhov@gmail.com>,
        "Rob Herring" <robh+dt@kernel.org>,
        "Krzysztof Kozlowski" <krzk+dt@kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] dt-bindings: input: Add bindings for Awinic AW8695
 haptics
References: <20220408115311.237039-1-luca.weiss@fairphone.com>
 <1a45984a-752b-6bad-0320-f0946d83f2b9@linaro.org>
 <CJ79EIW9Z89J.YZTZ6AU91TGE@otso>
 <60402ff3-db73-5fc0-bc2a-942d664085ec@linaro.org>
In-Reply-To: <60402ff3-db73-5fc0-bc2a-942d664085ec@linaro.org>
Precedence: bulk

Hi Krzysztof,

On Mon Apr 11, 2022 at 2:52 PM CEST, Krzysztof Kozlowski wrote:
> On 11/04/2022 10:15, Luca Weiss wrote:
>
> (...)
>
> >>> +  awinic,f0-detection-play-time:
> >>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>> +    description: Drive waveform play times in the first period in th=
e f0 detection
> >>
> >> Use standard unit suffixes for known units (e.g. time).
> >=20
> > While the datasheet doesn't mention any time unit, the value is used to
> > calculate the f0_trace_ms variable (which is milliseconds) but the
> > result also depends on the awinic,f0-preset value, so it's not a raw
> > time value.
>
> I see, ok.
>
> >=20
> >>
> >>> +
> >>> +  awinic,f0-detection-wait-time:
> >>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>> +    description: Waveform wait times in the f0 detection
> >>
> >> Ditto.
> >>
> >>> +
> >>> +  awinic,f0-detection-repeat:
> >>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>> +    description: Repeat times in the f0 detection
> >>> +
> >>> +  awinic,f0-detection-trace:
> >>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>> +    description: Drive waveform play times in the second period and =
later in the f0 detection
> >>> +
> >>> +  awinic,boost-debug:
> >>> +    $ref: /schemas/types.yaml#/definitions/uint8-array
> >>> +    minItems: 3
> >>> +    maxItems: 3
> >>> +    description: Values for BSTDBG1-3 registers
> >>
> >> Do not encode device programming model (registers) into the binding. Y=
ou
> >> need to define it as a property related to hardware itself, not its
> >> registers (e.g. boost value in mV).
> >=20
> > Unfortunately I couldn't figure the meaning for this and the two values
> > below.
> >=20
> > The datasheet doesn't mention these registers at all and the downstream
> > driver doesn't do anything meaningful with them (other than setting the=
m)
> > nor has any comment to indicate what they do.
> > In the datasheet there's only BSTDBG4 mentioned where bits [5:1] mean
> > PVDD output voltage setting so for these registers it could really be
> > anthing :(
> >=20
> > Maybe someone with more knowledge about LRAs might be able to decipher
> > what tset and r_spare is at least? I unfortunately didn't manage.
>
> Do you have to define them in such case in DT? Maybe it should be part
> of driver?

As these parameters are part of the dts downstream, I assume they differ
per board or actual LRA used.

But I also found other downstream dts examples on github (e.g.
awinic,aw8697_haptic) and they also seemed to use the same values for
these couple of registers (r_spare, tset and bstdbg). Maybe I can gather
more info but it's unlikely I'll be able to get a concrete answer..

Regards
Luca

>
> Best regards,
> Krzysztof