linux-kernel - Re: [PATCH v3 00/13] mfd: macsmc: add rtc, hwmon and hid subdevices

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Message-ID: <20251016221533.GD897177@robin.jannau.net>
Date: Fri, 17 Oct 2025 00:15:33 +0200
From: Janne Grunau <j@...nau.net>
To: James Calligeros <jcalligeros99@...il.com>
Cc: Sven Peter <sven@...nel.org>, Alyssa Rosenzweig <alyssa@...enzweig.io>,
	Neal Gompa <neal@...pa.dev>, Lee Jones <lee@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jonathan Corbet <corbet@....net>, asahi@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-rtc@...r.kernel.org,
	linux-hwmon@...r.kernel.org, linux-input@...r.kernel.org,
	linux-doc@...r.kernel.org, Mark Kettenis <kettenis@...nbsd.org>,
	Hector Martin <marcan@...can.st>
Subject: Re: [PATCH v3 00/13] mfd: macsmc: add rtc, hwmon and hid subdevices

On Tue, Oct 07, 2025 at 09:16:41PM +1000, James Calligeros wrote:
> Hi all,
> 
> This series adds support for the remaining SMC subdevices. These are the
> RTC, hwmon, and HID devices. They are being submitted together as the RTC
> and hwmon drivers both require changes to the SMC DT schema.
> 
> The RTC driver is responsible for getting and setting the system clock,
> and requires an NVMEM cell. This series replaces Sven's original RTC driver
> submission [1].
> 
> The hwmon function is an interesting one. While each Apple Silicon device
> exposes pretty similar sets of sensors, these all seem to be paired to
> different SMC keys in the firmware interface. This is true even when the
> sensors are on the SoC. For example, an M1 MacBook Pro will use different
> keys to access the LITTLE core temperature sensors to an M1 Mac mini. This
> necessitates describing which keys correspond to which sensors for each
> device individually, and populating the hwmon structs at runtime. We do
> this with a node in the device tree. This series includes only the keys
> for sensors which we know to be common to all devices. The SMC is also
> responsible for monitoring and controlling fan speeds on systems with fans,
> which we expose via the hwmon driver.

The split of the hwmon dts changes looks weird to me. It's not a lot of
changes so squashing everything together into a single commit might be
ok. If you want to split the commits splitting them by SoC (t8103,
t8112, t600x, ...) and adding common sensor defines as needed might work
better.

> The SMC also handles the hardware power button and lid switch. Power
> button presses and lid opening/closing are emitted as HID events, so we
> add an input subdevice to handle them.

The cover letter doesn't mention a merge strategy for this series. I
don't think there are any dependencies between different parts. That
means the dt-bindings and driver additions can be merged through their
subsystem trees. The single line patches wiring the devices up to the
macsmc mfd driver should be merged together through mfd tree as they
(trivially) conflict. The dts changes will be merged through the apple
soc tree.

Janne