linux-kernel - Re: [PATCH 1/3] dt-bindings: mfd: Add power-button option for TI TPS6594 PMIC

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Message-ID: <CAKMwjwSZEhXav2U-bd+JNyVDK3JdJoN1kJjnxpfKXBKsW2XxdQ@mail.gmail.com>
Date: Tue, 17 Jun 2025 12:07:24 -0400
From: Job Sava <jsava@...ticallink.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Lee Jones <lee@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Julien Panis <jpanis@...libre.com>, Dmitry Torokhov <dmitry.torokhov@...il.com>, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-input@...r.kernel.org, jcormier@...ticallink.com
Subject: Re: [PATCH 1/3] dt-bindings: mfd: Add power-button option for TI
 TPS6594 PMIC

On Tue, Jun 3, 2025 at 2:52 AM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> On 02/06/2025 15:07, Job Sava wrote:
> > On Thu, May 29, 2025 at 5:26 AM Krzysztof Kozlowski <krzk@...nel.org> wrote:
> >>
> >> On Fri, May 23, 2025 at 09:46:49AM GMT, Job Sava wrote:
> >>> On Wed, May 21, 2025 at 6:01 AM Krzysztof Kozlowski <krzk@...nel.org> wrote:
> >>>>
> >>>> On Tue, May 20, 2025 at 01:43:36PM GMT, Job Sava wrote:
> >>>>> The TPS6594 power-button option permits users to enter STANDBY or
> >>>>> ACTIVE state by a push, release, or short push button request.
> >>>>>
> >>>>> Signed-off-by: Job Sava <jsava@...ticallink.com>
> >>>>> ---
> >>>>>  Documentation/devicetree/bindings/mfd/ti,tps6594.yaml | 15 +++++++++++++++
> >>>>>  1 file changed, 15 insertions(+)
> >>>>>
> >>>>> diff --git a/Documentation/devicetree/bindings/mfd/ti,tps6594.yaml b/Documentation/devicetree/bindings/mfd/ti,tps6594.yaml
> >>>>> index 6341b6070366..a40808fd2747 100644
> >>>>> --- a/Documentation/devicetree/bindings/mfd/ti,tps6594.yaml
> >>>>> +++ b/Documentation/devicetree/bindings/mfd/ti,tps6594.yaml
> >>>>> @@ -37,6 +37,21 @@ properties:
> >>>>>        device on the SPMI bus, and the secondary PMICs are the target devices
> >>>>>        on the SPMI bus.
> >>>>>
> >>>>> +  ti,power-button:
> >>>>> +    type: boolean
> >>>>> +    description: |
> >>>>> +      Optional property that sets the EN/PB/VSENSE pin to be a
> >>>>> +      power-button.
> >>>>> +      TPS6594 has a multipurpose pin called EN/PB/VSENSE that can be either
> >>>>> +      1. EN in which case it functions as an enable pin.
> >>>>> +      2. VSENSE which compares the voltages and triggers an automatic
> >>>>> +      on/off request.
> >>>>> +      3. PB in which case it can be configured to trigger an interrupt
> >>>>> +      to the SoC.
> >>>>> +      ti,power-button reflects the last one of those options
> >>>>> +      where the board has a button wired to the pin and triggers
> >>>>> +      an interrupt on pressing it.
> >>>>
> >>>> Don't you need to handle two other cases as well? I assume you copied
> >>>> this from the other binding, but all three options are valid?
> >>>>
> >>>> Best regards,
> >>>> Krzysztof
> >>>>
> >>> Hello Krzysztof,
> >>>
> >>> Thank you for your response!
> >>>
> >>> I agree that the other two cases are valid options. However, for this
> >>> particular patch series, they may be out of scope. The primary goal of
> >>> this patch is to enable push-button functionality, rather than
> >>> addressing the VSENSE or EN modes.
> >>
> >> Binding should be complete, because if you design this as bool, it
> >> cannot be later changed to three-state (enum).
> >>
> >> I don't know if the EN and VSENSE modes are anyhow useful, maybe people
> >> interested in this hardware should say.
> >>
> >> Best regards,
> >> Krzysztof
> >>
> >
> > Hi Krzysztof,
> >
> > Thanks again for the feedback.
> >
> > I modeled this binding after the TPS65219 PMIC, which uses a boolean
>
> Yeah, that's what I meant in my first reply.
>
> > for ti,power-button, despite the same EN/PB/VSENSE options. Since this
> > patch only enables PB mode, I felt a boolean was appropriate and
> > consistent.
>
> Properties should have only one type, so that would be a different
> property.
Yes, the type is boolean.
> Someone knowing the device should come with arguments whether
> other states for this are useful at all. Or not useful and then argument
> that in commit msg for example.
The other states are not useful for the kernel. Only the push button
has a need for an interrupt handler. The other states the PMIC handles
on its own.

What exactly do you want me to change?

Best regards,
-Job
>
>
> Best regards,
> Krzysztof