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

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Message-ID: <f199fc0b-20c0-4c22-b0ed-c508514b60c6@kernel.org>
Date: Tue, 9 Sep 2025 08:56:36 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Linus Walleij <linus.walleij@...aro.org>,
 Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Ariel D'Alessandro <ariel.dalessandro@...labora.com>, airlied@...il.com,
 amergnat@...libre.com, andrew+netdev@...n.ch, andrew-ct.chen@...iatek.com,
 angelogioacchino.delregno@...labora.com, broonie@...nel.org,
 chunkuang.hu@...nel.org, ck.hu@...iatek.com, conor+dt@...nel.org,
 davem@...emloft.net, edumazet@...gle.com, flora.fu@...iatek.com,
 houlong.wei@...iatek.com, jeesw@...fas.com, jmassot@...labora.com,
 kernel@...labora.com, krzk+dt@...nel.org, kuba@...nel.org,
 kyrie.wu@...iatek.corp-partner.google.com, lgirdwood@...il.com,
 louisalexis.eyraud@...labora.com, maarten.lankhorst@...ux.intel.com,
 matthias.bgg@...il.com, mchehab@...nel.org, minghsiu.tsai@...iatek.com,
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 tzimmermann@...e.de, yunfei.dong@...iatek.com, devicetree@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org,
 linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
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 linux-sound@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v1 13/14] dt-bindings: input/touchscreen: Convert MELFAS
 MIP4 Touchscreen to YAML

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.


Best regards,
Krzysztof