linux-kernel - Re: [PATCH v2 3/6] dt-bindings: mfd: add max77759 binding

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAL_JsqK-_rPZqt_vRv75dSWDLUAyZ-LB=qz5J=Kse=7bO4q8sA@mail.gmail.com>
Date: Fri, 28 Feb 2025 07:01:35 -0600
From: Rob Herring <robh@...nel.org>
To: André Draszik <andre.draszik@...aro.org>
Cc: Lee Jones <lee@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Linus Walleij <linus.walleij@...aro.org>, 
	Bartosz Golaszewski <brgl@...ev.pl>, Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, 
	Kees Cook <kees@...nel.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
	Peter Griffin <peter.griffin@...aro.org>, Tudor Ambarus <tudor.ambarus@...aro.org>, 
	Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-gpio@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2 3/6] dt-bindings: mfd: add max77759 binding

On Thu, Feb 27, 2025 at 7:14 AM André Draszik <andre.draszik@...aro.org> wrote:
>
> On Thu, 2025-02-27 at 07:04 -0600, Rob Herring wrote:
> > On Wed, Feb 26, 2025 at 05:51:22PM +0000, André Draszik wrote:
> > > The Maxim MAX77759 is a companion PMIC for USB Type-C applications and
> > > includes Battery Charger, Fuel Gauge, temperature sensors, USB Type-C
> > > Port Controller (TCPC), NVMEM, and a GPIO expander.
> > >
> > > This describes the top-level device.
> > >
> > > Signed-off-by: André Draszik <andre.draszik@...aro.org>
> > >
> > > ---
> > > v2:
> > > * rename expected nvmem subdev nodename to 'nvmem-0'
> > >   I'd have preferred just 'nvmem', but that matches nvmem-consumer.yaml
> > >   and fails validation.
> > >
> > > Note: MAINTAINERS doesn't need updating, the binding update for the
> > > first leaf device (gpio) adds a wildcard matching all max77759 bindings
> > > ---
> > >  .../devicetree/bindings/mfd/maxim,max77759.yaml    | 104 +++++++++++++++++++++
> > >  1 file changed, 104 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/mfd/maxim,max77759.yaml b/Documentation/devicetree/bindings/mfd/maxim,max77759.yaml
> > > new file mode 100644
> > > index 0000000000000000000000000000000000000000..87e3737896a289998a18b67932dbccacfb8e3150
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/mfd/maxim,max77759.yaml
> > > @@ -0,0 +1,104 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/mfd/maxim,max77759.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Maxim Integrated MAX77759 PMIC for USB Type-C applications
> > > +
> > > +maintainers:
> > > +  - André Draszik <andre.draszik@...aro.org>
> > > +
> > > +description: |
> > > +  This is a part of device tree bindings for the MAX77759 companion Power
> > > +  Management IC for USB Type-C applications.
> > > +
> > > +  The MAX77759 includes Battery Charger, Fuel Gauge, temperature sensors, USB
> > > +  Type-C Port Controller (TCPC), NVMEM, and a GPIO expander.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: maxim,max77759
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  interrupt-controller: true
> > > +
> > > +  "#interrupt-cells":
> > > +    const: 2
> > > +
> > > +  gpio-controller: true
> > > +
> > > +  "#gpio-cells":
> > > +    const: 2
> >
> > Why do you have GPIO properties here and in the child node? Either would
> > be valid, but both probably not. Putting them here is actually
> > preferred.
>
> That's an oversight, I meant to put them into the child only, not here,
> since the child is the one providing the gpio functionality.
>
> What's the reason to have it preferred inside this parent node?

It really depends whether the GPIO block is a separate sub-block which
is going to get reused or has its own resources or not. It's the same
thing in system controllers which are often just a collection of
leftover control bits.

We just don't want child nodes created just for the ease of
instantiating drivers in Linux. While it's nice if drivers and nodes
are 1 to 1, but that's specific to an OS.

You already need other child nodes here, so I don't care too much in this case.

Rob