Re: [PATCH v5 1/8] soc: bcm2835: Use IS_REACHABLE for function declaration

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Misuse of IS_REACHABLE to hide Kconfig dependency mismatches, leading to silent runtime failures.
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commit dcaefe39201e65d292203c3c769d9af92e05fa3c
Author: Gregor Herburger <gregor.herburger@linutronix.de>
soc: bcm2835: Use IS_REACHABLE for function declaration

This commit modifies the raspberrypi-firmware header to use IS_REACHABLE() 
instead of IS_ENABLED(). The goal is to simplify Kconfig dependencies for 
drivers relying on RASPBERRYPI_FIRMWARE and avoid linker errors when 
COMPILE_TEST is enabled.

> diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
> index e1f87fbfe5542..eb33838e0cd10 100644
> --- a/include/soc/bcm2835/raspberrypi-firmware.h
> +++ b/include/soc/bcm2835/raspberrypi-firmware.h
> @@ -174,7 +174,7 @@ struct rpi_firmware_clk_rate_request {
>  		.id = cpu_to_le32(_id),		\
>  	}
>  
> -#if IS_ENABLED(CONFIG_RASPBERRYPI_FIRMWARE)
> +#if IS_REACHABLE(CONFIG_RASPBERRYPI_FIRMWARE)

[Severity: Medium]
Does using IS_REACHABLE() here risk silent runtime failures?

If a dependent driver is built-in (=y) while RASPBERRYPI_FIRMWARE=m 
(which becomes possible when changing the Kconfig to just 
depends on RASPBERRYPI_FIRMWARE || COMPILE_TEST), IS_REACHABLE() evaluates 
to false.

Instead of Kbuild catching the dependency mismatch with a visible link error, 
the compiler will silently substitute dummy inline implementations for the 
firmware API calls. This allows the built-in driver to compile and link 
successfully, but it will fail at runtime (e.g., rpi_firmware_get()
returning NULL).

Was the original Kconfig expression explicitly structured to catch this 
built-in vs module dependency mismatch at configuration time rather than 
hiding it at runtime?

>  int rpi_firmware_property(struct rpi_firmware *fw,
>  			  u32 tag, void *data, size_t len);

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Sashiko AI review · https://sashiko.dev/#/patchset/20260520-rpi-otp-driver-v5-0-b26e5908eeac@linutronix.de?part=1