Re: [PATCH v9 3/6] mfd: khadas-mcu: Add support for VIM4 MCU variant

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The driver unconditionally fails to probe on generic Khadas MCU boards (VIM1/VIM2/VIM3) due to a NULL pointer check on valid match data.
--

--- Patch [3]: [PATCH v9 3/6] mfd: khadas-mcu: Add support for VIM4 MCU variant ---
commit eab418dac1b5e94bd297b0a14e92e87b2063dc9b
Author: Ronald Claveau <[email protected]>

mfd: khadas-mcu: Add support for VIM4 MCU variant

This patch refactors the probe function to use per-variant values instead of
hardcoded globals. It adds dedicated regmap configuration, fan control register,
and duty-cycle levels for the VIM4 MCU variant. A new compatible string
"khadas,vim4-mcu" is introduced for this new device.

> diff --git a/drivers/mfd/khadas-mcu.c b/drivers/mfd/khadas-mcu.c
> index 0e74efe14f367..4cb305ac915e1 100644
> --- a/drivers/mfd/khadas-mcu.c
> +++ b/drivers/mfd/khadas-mcu.c
[ ... ]
> @@ -75,47 +75,138 @@ static const struct regmap_config khadas_mcu_regmap_config = {
[ ... ]
>  static int khadas_mcu_probe(struct i2c_client *client)
>  {
> +	const struct mfd_cell *cells, *fan_cells;
> +	const struct regmap_config *regmap_cfg;
>  	struct device *dev = &client->dev;
> +	int ncells, nfan_cells, ret;
>  	struct khadas_mcu *ddata;
> -	int ret;
> +	const void *match;
>  
>  	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
>  	if (!ddata)
>  		return -ENOMEM;
>  
> +	match = i2c_get_match_data(client);
> +	if (!match)
> +		return -ENODEV;

[Severity: High]
Does this code inadvertently break the probe for generic Khadas MCU boards
(VIM1/VIM2/VIM3)?

Because KHADAS_MCU_GENERIC evaluates to 0 in its enum, i2c_get_match_data() will
return a NULL pointer when matching "khadas,mcu" in khadas_mcu_probe() in
drivers/mfd/khadas-mcu.c. This will cause the check here to evaluate to true and
unconditionally abort the probe with -ENODEV.

[ ... ]
> @@ -123,7 +214,8 @@ static int khadas_mcu_probe(struct i2c_client *client)
>  
>  #ifdef CONFIG_OF
>  static const struct of_device_id khadas_mcu_of_match[] = {
> -	{ .compatible = "khadas,mcu", },
> +	{ .compatible = "khadas,mcu", .data = (void *)KHADAS_MCU_GENERIC },
> +	{ .compatible = "khadas,vim4-mcu", .data = (void *)KHADAS_MCU_VIM4 },
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, khadas_mcu_of_match);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=3