Re: [PATCH 2/3] nvmem: Add driver for i.MX BBNSM GP register

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] nvmem: imx-bbnsm: missing MFD_SYSCON dependency in Kconfig
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commit 72a81833b2595fcf0c62fe0c32408d53d3b1d63b
Author: Stefan Wahren <wahrenst@gmx.net>

nvmem: Add driver for i.MX BBNSM GP register

This commit adds an NVMEM provider driver to expose the general purpose
registers in the Battery-Backed Non-Secure Module (BBNSM) on i.MX9 SoCs.

> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index c36c2a4c2a0b7..8d492d05f1602 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -185,6 +185,18 @@ config NVMEM_BRCM_NVRAM
>  	  This driver provides support for Broadcom's NVRAM that can be accessed
>  	  using I/O mapping.
>  
> +config NVMEM_IMX_BBNSM
> +	tristate "i.MX BBNSM general purpose register support"
> +	depends on ARCH_MXC || COMPILE_TEST
> +	depends on OF
> +	select REGMAP_MMIO

[Severity: Low]
Should NVMEM_IMX_BBNSM depend on or select MFD_SYSCON instead of selecting
REGMAP_MMIO?

In drivers/nvmem/imx-bbnsm.c, imx_bbnsm_probe() obtains its regmap via
syscon_node_to_regmap(parent) rather than calling any regmap-mmio API
directly:

	priv->regmap = syscon_node_to_regmap(parent);
	of_node_put(parent);
	if (IS_ERR(priv->regmap))
		return PTR_ERR(priv->regmap);

On arm64, ARCH_MXC does not select MFD_SYSCON (unlike 32-bit ARCH_MXC). When
CONFIG_MFD_SYSCON is disabled, syscon_node_to_regmap() in
include/linux/mfd/syscon.h falls back to its inline stub returning
ERR_PTR(-ENOTSUPP), causing imx_bbnsm_probe() to fail unconditionally at
runtime. MFD_SYSCON also already selects REGMAP_MMIO.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261101200140.141642-1-wahrenst@gmx.net?part=2