Re: [PATCH RFC v3 01/17] firmware: arm_scmi: Drop the ARM architecture dependency

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] firmware: arm_scmi: missing HAS_IOMEM dependency on ARM_SCMI_PROTOCOL
--

commit 2b45f4669350cda60b185c5a0c439cbdd7f35cc9
Author: Han Gao <gaohan@iscas.ac.cn>

firmware: arm_scmi: Drop the ARM architecture dependency

This commit removes the ARM, ARM64, and COMPILE_TEST dependency from
ARM_SCMI_PROTOCOL in Kconfig so that other architectures can build and use
the SCMI protocol driver.

> diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
> index 783c24a20e291..b56aed46a3870 100644
> --- a/drivers/firmware/arm_scmi/Kconfig
> +++ b/drivers/firmware/arm_scmi/Kconfig
> @@ -3,7 +3,6 @@ menu "ARM System Control and Management Interface Protocol"
>  
>  config ARM_SCMI_PROTOCOL
>  	tristate "ARM System Control and Management Interface (SCMI) Message Protocol"
> -	depends on ARM || ARM64 || COMPILE_TEST

[Severity: Low]
Should ARM_SCMI_PROTOCOL retain a dependency on HAS_IOMEM?

Previously, ARM and ARM64 selected HAS_IOMEM, and COMPILE_TEST in
init/Kconfig depends on HAS_IOMEM, which guaranteed that CONFIG_HAS_IOMEM
was enabled whenever ARM_SCMI_PROTOCOL was selectable. Dropping this line
leaves ARM_SCMI_PROTOCOL with no dependencies, allowing it to be enabled on
targets where CONFIG_HAS_IOMEM is disabled (such as ARCH=um).

When CONFIG_ARM_SCMI_PROTOCOL is enabled, the core driver in
drivers/firmware/arm_scmi/driver.c unconditionally compiles
scmi_common_fastchannel_init(), which calls devm_ioremap():

    addr = devm_ioremap(ph->dev, phys_addr, size);

In addition, when CONFIG_MAILBOX or CONFIG_OPTEE is enabled,
ARM_SCMI_TRANSPORT_MAILBOX or ARM_SCMI_TRANSPORT_OPTEE selects
ARM_SCMI_HAVE_SHMEM, which compiles drivers/firmware/arm_scmi/shmem.c
(calling __ioread32_copy() in shmem_memcpy_fromio32(), __iowrite32_copy()
in shmem_memcpy_toio32(), and devm_ioremap() in shmem_setup_iomap()) and
drivers/firmware/arm_scmi/transports/mailbox.c (calling devm_iounmap() in
mailbox_chan_setup()).

Because lib/Makefile only builds iomap_copy.o and devres.o when
CONFIG_HAS_IOMEM is enabled:

    obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o

won't building ARM_SCMI_PROTOCOL with CONFIG_HAS_IOMEM disabled fail at link
time with undefined references to devm_ioremap(), devm_iounmap(),
__ioread32_copy(), and __iowrite32_copy()?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-a210-scmi-v3-0-ee6b31580808@iscas.ac.cn?part=1