linux-kernel - Re: [PATCH v2 4/7] dt-bindings: input: matrix_keypad

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Message-ID: <20241106-mobility-exorcist-34d53a6303a3@spud>
Date: Wed, 6 Nov 2024 16:24:27 +0000
From: Conor Dooley <conor@...nel.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Markus Burri <markus.burri@...com>, linux-kernel@...r.kernel.org,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Marek Vasut <marek.vasut@...il.com>, linux-input@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v2 4/7] dt-bindings: input: matrix_keypad - add missing
 property

On Tue, Nov 05, 2024 at 11:14:32AM -0800, Dmitry Torokhov wrote:
> Hi Conor,
> 
> On Tue, Nov 05, 2024 at 06:22:36PM +0000, Conor Dooley wrote:
> > On Tue, Nov 05, 2024 at 02:03:19PM +0100, Markus Burri wrote:
> > > Add missing property 'gpio-activelow' to DT schema.
> > 
> > What do you mean "missing property"? Why isn't it sufficient to mark the
> > GPIOs as GPIO_ACTIVE_LOW in the various -gpios properties?
> 
> Unfortunately we do have "gpio-activelow" property already used in the
> driver since 2012 when DT support was added to the driver. This patch
> merely acknowledges that it is there.
> 
> If DT maintainers wish to adjust known DTSes and switch to proper
> polarity annotation through gpio property I am all for it.

If that's the rationale, it should be in the commit message. It's not my
job to figure out people's intentions :)

> > > Signed-off-by: Markus Burri <markus.burri@...com>
> > > ---
> > >  .../devicetree/bindings/input/gpio-matrix-keypad.yaml        | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/input/gpio-matrix-keypad.yaml b/Documentation/devicetree/bindings/input/gpio-matrix-keypad.yaml
> > > index 745652b..9ea66b3 100644
> > > --- a/Documentation/devicetree/bindings/input/gpio-matrix-keypad.yaml
> > > +++ b/Documentation/devicetree/bindings/input/gpio-matrix-keypad.yaml
> > > @@ -51,6 +51,11 @@ properties:
> > >        (Legacy property supported: "linux,wakeup")
> > >      default: false
> > >  
> > > +  gpio-activelow:
> > > +    type: boolean
> > > +    description: The GPIOs are low active.
> > > +    default: false
> > 
> > What you want is a flag, not a boolean here btw. Flags you can check for
> > the presence of, booleans you cannot.
> 
> The behavior is fixed.

What do you mean by "fixed"? Corrected, unchangeable or something else?

> If the flag is true GPIO is assumed to be active
> low, otherwise (and in the absence of the flag) GPIO is assumed to be
> active high.

Flags cannot be false only true or absent, what you have described here
is a boolean.

> 
> > 
> > > +
> > >    debounce-delay-ms:
> > >      description: Debounce interval in milliseconds.
> > >      default: 0
> > > -- 
> > > 2.39.5
> > > 
> 
> Thanks.
> 
> -- 
> Dmitry

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