Re: [PATCH v15 3/6] mfd: mc33978: Add NXP MC33978/MC34978 MSDI support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The MFD core driver logic is located outside the drivers/mfd/ directory, which violates the MFD subsystem architectural layering guidelines.
--

--- Patch [3]: [PATCH v15 3/6] mfd: mc33978: Add NXP MC33978/MC34978 MSDI support ---
commit 09f08b1f8383cdd24c190a2b668c57a0b16e814d
Author: Oleksij Rempel <o.rempel@pengutronix.de>

mfd: mc33978: Add NXP MC33978/MC34978 MSDI support

This commit adds the Multi-Function Device (MFD) driver for the NXP MC33978
and MC34978 Multiple Switch Detection Interfaces (MSDI), setting up the SPI
device, regulators, and instantiating child devices.

> diff --git a/drivers/mfd/mc33978.c b/drivers/mfd/mc33978.c
> new file mode 100644
> --- /dev/null
> +++ b/drivers/mfd/mc33978.c
[ ... ]
> +static int mc33978_probe(struct spi_device *spi)
> +{
[ ... ]
> +	/*
> +	 * Core module creates regmap/IRQ domain/event handling. Separated
> +	 * because custom SPI protocol needs complex regmap_bus implementation.
> +	 *
> +	 * API contract: mc33978_core_init() initializes domain_out to NULL on
> +	 * entry. On success (return 0), domain_out is guaranteed to point to a
> +	 * valid IRQ domain. On error, domain_out remains NULL. This allows
> +	 * safe dereference of ddata->domain below without NULL check after
> +	 * verifying ret == 0.
> +	 */
> +	ret = mc33978_core_init(dev, spi, &ddata->domain);
> +	if (ret)
> +		return ret;

[Severity: Medium]
Does this violate the MFD subsystem architectural layering guidelines?

The MFD core driver logic, including regmap setup, IRQ domains, and event
harvesting, appears to be located outside the drivers/mfd/ directory in
mc33978_core_init().

As noted in the commit message, the core driver was placed in platform/misc.
Subsystem rules require core MFD drivers and logic to be located in
drivers/mfd/ to ensure the complex parts of the driver receive proper
maintainer review. Placing it outside bypasses this process.

Could this core logic be moved into drivers/mfd/ alongside the rest of the
MFD registration?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260710101358.2606941-1-o.rempel@pengutronix.de?part=3