Re: [PATCH v2 2/2] rtc: efi: defer to the ACPI TAD if it can drive the RTC

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] rtc: efi: ACPI_TAD dependency disables RTC_DRV_EFI in arm64 defconfig
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commit 43949693bace16600c49e8c7dd525850e1286516
Author: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>

rtc: efi: defer to the ACPI TAD if it can drive the RTC

This commit updates efi_rtc_probe() in drivers/rtc/rtc-efi.c to return
-ENODEV when acpi_has_rtc() is true, and makes RTC_DRV_EFI depend on
!ACPI || ACPI_TAD.

> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 1e863f1d36fd5..26f057f52ce59 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1262,10 +1262,14 @@ config RTC_DRV_DA9063
>  config RTC_DRV_EFI
>  	tristate "EFI RTC"
>  	depends on EFI && !X86
> +	depends on !ACPI || ACPI_TAD

[Severity: High]
Does adding "depends on !ACPI || ACPI_TAD" here cause CONFIG_RTC_DRV_EFI=y
to be silently dropped in arch/arm64/configs/defconfig (and existing
configurations with CONFIG_ACPI=y and CONFIG_ACPI_TAD=n)?

In drivers/acpi/Kconfig, ACPI_TAD has no default and depends on SYSFS and
PM_SLEEP:

config ACPI_TAD
	tristate "ACPI Time and Alarm (TAD) Device Support"
	depends on SYSFS && PM_SLEEP

In arch/arm64/configs/defconfig, CONFIG_ACPI=y and CONFIG_RTC_DRV_EFI=y are
enabled without setting CONFIG_ACPI_TAD, so this dependency causes Kconfig
to drop CONFIG_RTC_DRV_EFI while leaving CONFIG_ACPI_TAD disabled,
resulting in neither rtc-efi nor acpi-tad being built. It also prevents
enabling CONFIG_RTC_DRV_EFI when CONFIG_ACPI=y and CONFIG_PM_SLEEP=n (or
CONFIG_SYSFS=n).

Since include/linux/acpi.h already provides an inline stub for
acpi_has_rtc() when !IS_REACHABLE(CONFIG_ACPI_TAD):

#if IS_REACHABLE(CONFIG_ACPI_TAD)
bool acpi_has_rtc(void);
#else
static inline bool acpi_has_rtc(void) { return false; }
#endif

should this use "depends on ACPI_TAD || !ACPI_TAD" instead to avoid the
CONFIG_RTC_DRV_EFI=y and CONFIG_ACPI_TAD=m reachability mismatch, or if
ACPI_TAD is meant to be required whenever ACPI is enabled, should ACPI_TAD
and defconfig be updated accordingly?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261023212218.2568858-1-hamzamahfooz@linux.microsoft.com?part=2