[PATCH] iommu: Tidy up io-pgtable dependencies

[Conor Dooley]

Hey Robin,

On Thu, Jan 12, 2023 at 07:59:47PM +0000, Robin Murphy wrote:
> Some io-pgtable implementations, and thus their users too, carry a
> slightly odd dependency to get around the GENERIC_ATOMIC64 version of
> cmpxchg64() often failing to compile. Since this is a functional
> dependency, it's a bit misleading and untidy to tie it explicitly to
> COMPILE_TEST while assuming that it's also implied by the other
> platform/architecture options. Make things clearer by separating these
> functional dependencies into distinct statements from those controlling
> visibility, and since they do look a bit non-obvious to the uninitiated,
> also commenting them for good measure.
> 
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>
> ---
>  drivers/iommu/Kconfig | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)

>  config IPMMU_VMSA
>  	bool "Renesas VMSA-compatible IPMMU"
> -	depends on ARCH_RENESAS || (COMPILE_TEST && !GENERIC_ATOMIC64)
> +	depends on ARCH_RENESAS || COMPILE_TEST
> +	depends on !GENERIC_ATOMIC64	# for IOMMU_IO_PGTABLE_LPAE
>  	select IOMMU_API
>  	select IOMMU_IO_PGTABLE_LPAE
>  	select ARM_DMA_USE_IOMMU

This is a fix for the broken riscv32 allmodconfig stuff that Palmer
reported, right?
https://lore.kernel.org/all/20221214180409.7354-1-palmer@rivosinc.com/

I did a dfn:drivers/iommu/Kconfig search on lore & saw this, but AFAICT
the patch was applied to next rather than fixes.

Apologies if I'm off here, I have had that report in my follow-up-on
queue for a while & since Christmas happened in between I've lost track
of when the build failure was introduced.

Last I remember, Guo Ren sent a patch that was not to your liking, but I
didn't see anything after that.

Thanks,
Conor.
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