Re: [RFC v2 02/39] ACPI: add dependency on HAS_IOPORT

[Bjorn Helgaas]

On Fri, Apr 29, 2022 at 03:50:00PM +0200, Niklas Schnelle wrote:
> In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> not being declared. As ACPI always uses I/O port access we simply depend
> on HAS_IOPORT.

CONFIG_ACPI depends on ARCH_SUPPORTS_ACPI, which is only set by arm64,
ia64, and x86, all of which support I/O port access.  So does this
actually solve a problem?  I wouldn't think you'd be able to build
ACPI on s390 even without this patch.

"ACPI always uses I/O port access" is a pretty broad brush, and it
would be useful to know specifically what the dependencies are.

Many ACPI hardware accesses use acpi_hw_read()/acpi_hw_write(), which
use either MMIO or I/O port accesses depending on what the firmware
told us.

> Co-developed-by: Arnd Bergmann <arnd@xxxxxxxxxx>
> Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
> ---
>  drivers/acpi/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 1e34f846508f..8ad0d168004c 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -5,6 +5,7 @@
>  
>  config ARCH_SUPPORTS_ACPI
>  	bool
> +	depends on HAS_IOPORT
>  
>  menuconfig ACPI
>  	bool "ACPI (Advanced Configuration and Power Interface) Support"
> -- 
> 2.32.0
>