Re: [PATCH v2] hwmon: Add driver for MSI Mystic Light controller voltage sensors

[Guenter Roeck <linux@roeck-us.net>]

On Sat, Nov 07, 2026 at 09:28:21AM +0100, Tomasz Bojanowski wrote:
> MSI 800-series motherboards have a USB microcontroller (0db0:0076) that
> drives the RGB LED headers. Besides the LEDs, it measures a few voltage
> rails that are not monitored by the Super I/O chip, and reports them in
> HID feature report 0xf0.
> 
> Add a driver that reads this report and exposes the rails as standard
> hwmon voltage attributes with labels. The values are cached for one
> second. The driver never writes to the device and keeps the hidraw
> interface, so user space tools that control the LEDs through hidraw keep
> working.
> 
> The controller has the same USB ID on different boards, while the rails
> and their position in the report depend on the board. The driver is
> therefore only registered on supported boards, which are matched by DMI.
> On other boards the device stays with hid-generic. Probe reads the
> report once, fails if it cannot be read or has an unexpected format, and
> only exposes the rails that return a reading. For now only the MAG B850M
> MORTAR WIFI (MS-7E61) is supported.
> 
> The report layout was determined by analysing the vendor's Windows
> software and confirmed on hardware.
> 
> Tested on an MSI MAG B850M MORTAR WIFI (MS-7E61, BIOS 1.A68), with the
> driver built out of tree against kernel 7.2.15. The readings (CPU 1P8
> 1.79 V, CHIP Core 1.04 V, VDD MISC 1.10 V) are stable and plausible for
> the respective rails, repeated reads within one second are served from
> the cache, and hidraw access works while the driver is bound. Loading
> and unloading the module repeatedly hands the device back to hid-generic
> without errors.
> 
> Signed-off-by: Tomasz Bojanowski <tomasz@bojanowski.me>

Applied.

Again, I'll be happy to test with older boards. Alternatively, I might give
adding support to older boards a try if you can provide information how
to access the sensors on those boards.

Thanks,
Guenter