linux-kernel - Re: [PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom touchscreen

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Message-ID: <94bf91fc-9f6e-491f-b332-d60e69ebd9d6@linaro.org>
Date: Wed, 31 Jan 2024 11:59:09 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Kamel Bouhara <kamel.bouhara@...tlin.com>
Cc: Rob Herring <robh@...nel.org>, Dmitry Torokhov
 <dmitry.torokhov@...il.com>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>, Henrik Rydberg <rydberg@...math.org>,
 linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, Marco Felsch <m.felsch@...gutronix.de>,
 Jeff LaBundy <jeff@...undy.com>, catalin.popescu@...ca-geosystems.com,
 mark.satterthwaite@...chnetix.com,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 Gregory Clement <gregory.clement@...tlin.com>,
 bsp-development.geo@...ca-geosystems.com
Subject: Re: [PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom
 touchscreen

On 31/01/2024 10:06, Kamel Bouhara wrote:
> Hello,
> 
> On Wed, Jan 31, 2024 at 08:28:43AM +0100, Krzysztof Kozlowski wrote:
>> On 30/01/2024 23:28, Rob Herring wrote:
>>> On Fri, Jan 26, 2024 at 12:46:16PM +0100, Krzysztof Kozlowski wrote:
>>>> On 25/01/2024 17:58, Kamel Bouhara wrote:
>>>>> +  reset-gpios:
>>>>> +    maxItems: 1
>>>>> +
>>>>> +  vdda-supply:
>>>>> +    description: Analog power supply regulator on VDDA pin
>>>>> +
>>>>> +  vddi-supply:
>>>>> +    description: I/O power supply regulator on VDDI pin
>>>>> +
>>>>> +  startup-time-ms:
>>>>> +    description: delay after power supply regulator is applied in ms
>>>>
>>>> That's a regulator property - ramp up time.
>>>
>>> I'm sure there's an existing property name that could be used.
>>>
>>> But why is it needed? Is it variable per board with the same device? If
>>> not, it should be implied by the compatible.
>>
>> I meant, that regulators have such property. Unless this is coming from
>> the device needs, not from the regulator?
>>
> 
> After looking again into the device's datasheet [1], the delay (startup
> time) is not really optional and it shouldn't be set through devicetree.
> 
> IIUC, it have to be set unconditionally after a device reset or
> a vdda assertion.
> 
> [1]: https://www.touchnetix.com/media/dgnjohor/tnxd00394-a3-axiom_ax54a_2d_touch_controller_datasheet.pdf
> --

OK, then it's not a regulator ramp up, but rather part of device driver
(deduced from compatible).

Best regards,
Krzysztof