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

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Message-Id: <DBHJ1S8MTSA2.35ZZDZFQGFNB1@kernel.org>
Date: Mon, 21 Jul 2025 08:42:32 +0200
From: "Michael Walle" <mwalle@...nel.org>
To: "Jon Cormier" <jcormier@...ticallink.com>, "Jerome Neanne"
 <jneanne@...libre.com>, "Markus Schneider-Pargmann" <msp@...libre.com>
Cc: "Job Sava" <jsava@...ticallink.com>, "Krzysztof Kozlowski"
 <krzk@...nel.org>, "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>
Subject: Re: [PATCH 1/3] dt-bindings: mfd: Add power-button option for TI
 TPS6594 PMIC

[+ Jerome and Markus ]

Hi,

> > > > 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?
> >
> > Because the driver isn't setting the configuration anyway, wouldn't
> > it be possible to read the config bits (Register 0x3c, bits 7-6) to
> > figure out whether the pin is configured as power-button instead of
> > having this property?
> >
> > I mean, the correct config is likely stored in the NVM anyway, and
> > reconfiguring it to another value seems unlikely.
> Currently, the TPS MFD driver only loads the power button driver if
> the flag is set.  We could put that discovery code in the MFD driver,
> but what if the system designer doesn't want the power button driver?

The device tree is not for configuration. The designer can just
ignore the input event in that case.

> I'm not sure auto detecting it makes sense.

Why?

> We are basing this on the other TI PMIC drivers and how they are
> configured. I'm not sure I want to reinvent the wheel, so to speak.

That was never a good reason. Maybe there was a reason for the
TPS65219. Markus? Jerome? I haven't found anything in the commit
messages or cover letters. Only that it is "optional". Not sure what
that means. According to the TPS65219 datasheet, that pin if not
used shall be configured as EN and be connected to VSYS.

-michael

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