linux-kernel - Re: [PATCH v1 13/14] dt-bindings: input/touchscreen: Convert MELFAS MIP4 Touchscreen to YAML

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Message-ID: <7523752e-eb7b-4211-84f2-33916c39ee2b@collabora.com>
Date: Wed, 10 Sep 2025 13:01:07 -0300
From: Ariel D'Alessandro <ariel.dalessandro@...labora.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 Linus Walleij <linus.walleij@...aro.org>,
 Dmitry Torokhov <dmitry.torokhov@...il.com>
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Subject: Re: [PATCH v1 13/14] dt-bindings: input/touchscreen: Convert MELFAS
 MIP4 Touchscreen to YAML

Krzysztof, all,

On 9/9/25 3:56 AM, Krzysztof Kozlowski wrote:
> On 05/09/2025 13:33, Linus Walleij wrote:
>> On Fri, Sep 5, 2025 at 12:02 PM Dmitry Torokhov
>> <dmitry.torokhov@...il.com> wrote:
>>> On Thu, Aug 21, 2025 at 01:56:24PM +0200, Linus Walleij wrote:
>>>> Hi Ariel,
>>>>
>>>> thanks for your patch!
>>>>
>>>> On Wed, Aug 20, 2025 at 7:17 PM Ariel D'Alessandro
>>>> <ariel.dalessandro@...labora.com> wrote:
>>>>
>>>>> +  ce-gpios:
>>>>> +    description: GPIO connected to the CE (chip enable) pin of the chip
>>>>> +    maxItems: 1
>>>>
>>>> Mention that this should always have the flag GPIO_ACTIVE_HIGH
>>>> as this is required by the hardware.
>>>>
>>>> Unfortunately we have no YAML syntax for enforcing flags :/
>>>
>>> Theoretically there can be an inverter on the line, so from the AP point
>>> of view the line is active low while from the peripheral POV the pin is
>>> active high...
>>
>> Yes, I think someone even proposed adding inverters to the
>> device tree and was nixed.
> 
> It's not about DT, it's about board design - you can (almost?) always
> invert the logical signal, so this should match what hardware requires
> plus any inverter on the board.
> 
> 
>>
>> It's a matter of phrasing I would say:
>>
>> "Mention that this should nominally have the flag GPIO_ACTIVE_HIGH
> 
> No, please do not, it is wrong. If hardware requires active high, then
> just say this is active high. But the actual GPIO flag depends on the
> board design if signal is inverted.

After the discussion from this thread, will mark it a "active high" in 
the property description for v2.

Thanks,

-- 
Ariel D'Alessandro
Software Engineer

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