Re: [PATCH v6 5/6] mfd: motorola-cpcap: diverge configuration per-board

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Critical] Modifying the OF match table breaks backward compatibility with existing Device Trees.
- [Low] Casting a pointer directly to an enum causes a `-Wpointer-to-int-cast` compiler warning on 64-bit architectures.
--

commit d4fffaca1e4a78c4406875cbdeef7c59b0fe0b1a
Author: Svyatoslav Ryhel <clamor95@gmail.com>

mfd: motorola-cpcap: diverge configuration per-board

This commit introduces board-specific subdevice configurations for the
Motorola CPCAP MFD. It defines common, default, and mapphone device lists
and uses SPI/OF match data to select the variant.

> diff --git a/drivers/mfd/motorola-cpcap.c b/drivers/mfd/motorola-cpcap.c
> index d8243b956f875..5b6ca6b81c232 100644
> --- a/drivers/mfd/motorola-cpcap.c
> +++ b/drivers/mfd/motorola-cpcap.c
[ ... ]
> @@ -241,62 +229,58 @@ static int cpcap_resume(struct device *dev)
[ ... ]
>  static int cpcap_probe(struct spi_device *spi)
>  {
>  	struct cpcap_ddata *cpcap;
> +	const struct mfd_cell *cells;
> +	unsigned int num_cells;
>  	int ret;
>  
>  	cpcap = devm_kzalloc(&spi->dev, sizeof(*cpcap), GFP_KERNEL);
>  	if (!cpcap)
>  		return -ENOMEM;
>  
> +	cpcap->variant = (enum cpcap_variant)spi_get_device_match_data(spi);

[Severity: Low]
Does this direct cast from a pointer to an enum cause a compiler warning on
64-bit architectures?

spi_get_device_match_data() returns a const void *, which is 64-bit on
64-bit architectures, while enum cpcap_variant is typically a 32-bit integer.
Casting directly from a 64-bit pointer to a 32-bit enum can trigger a
-Wpointer-to-int-cast warning and cause build failures when compiled with
-Werror.

Should the pointer be cast to an intermediate integer type like
(uintptr_t) or (unsigned long) first?

[ ... ]
> @@ -331,10 +315,29 @@ static int cpcap_probe(struct spi_device *spi)
[ ... ]
> +static const struct of_device_id cpcap_of_match[] = {
> +	{ .compatible = "motorola,cpcap", .data = (void *)CPCAP_DEFAULT },
> +	{ .compatible = "motorola,mapphone-cpcap", .data = (void *)CPCAP_MAPPHONE },
> +	{ /* sentinel */ }
> +};

[Severity: Critical]
Does this modification to the OF match table break backward compatibility with
existing Device Trees?

The Device Tree is considered a stable ABI in the kernel. This change reassigns
the existing "motorola,cpcap" compatible string to map to CPCAP_DEFAULT instead
of preserving its legacy behavior (which included Mapphone-specific child
nodes).

Older DTBs rely on "motorola,cpcap" to instantiate devices such as the battery
charger and Mapphone-specific ADC/regulator/USB-PHY. By mapping to
CPCAP_DEFAULT, the MFD core uses generic compatible strings (e.g.,
"motorola,cpcap-adc" instead of "motorola,mapphone-cpcap-adc") and entirely
omits the charger. As a result, the child devices fail to match their DT nodes,
leaving them without of_node pointers and breaking critical functionality.

Additionally, could the complete removal of the "st,6556002" compatible string
(mentioned in the commit message) break devices relying on it?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260520182124.117863-1-clamor95@gmail.com?part=5