[PATCH] RISC-V: Disable IPMMU_VMSA on rv32

[Robin Murphy]

On 2022-12-14 21:40, Prabhakar Mahadev Lad wrote:
> Hi,
> 
>> -----Original Message-----
>> From: Robin Murphy <robin.murphy at arm.com>
>> Sent: 14 December 2022 21:04
>> To: Conor Dooley <conor at kernel.org>; linux-riscv at lists.infradead.org; Palmer Dabbelt
>> <palmer at rivosinc.com>; arnd at arndb.de; iommu at lists.linux.dev
>> Cc: Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj at bp.renesas.com>
>> Subject: Re: [PATCH] RISC-V: Disable IPMMU_VMSA on rv32
>>
>> On 2022-12-14 19:46, Conor Dooley wrote:
>>>
>>>
>>> On 14 December 2022 10:04:09 GMT-08:00, Palmer Dabbelt <palmer at rivosinc.com> wrote:
>>>> Without this I get a Kconfig warning and then subsequent build
>>>> failure when building allmodconfig on rv32.
>>>>
>>>> WARNING: unmet direct dependencies detected for IOMMU_IO_PGTABLE_LPAE
>>>>    Depends on [n]: IOMMU_SUPPORT [=y] && (ARM || ARM64 || COMPILE_TEST [=y] && !GENERIC_ATOMIC64
>> [=y])
>>>>    Selected by [y]:
>>>>    - IPMMU_VMSA [=y] && IOMMU_SUPPORT [=y] && (ARCH_RENESAS [=y] ||
>>>> COMPILE_TEST [=y]
>>>
>>> This here is your problem afaict
>>> I got a report from lkp about it yesterday, "blaming" Prabhakar for it:
>>> https://jpn01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore
>>> .kernel.org%2Fall%2F202212142355.b7vf3Jh0-lkp%40intel.com%2F&data=
>>> 05%7C01%7Cprabhakar.mahadev-lad.rj%40bp.renesas.com%7Ca51ccd27ccda45e7
>>> 53c208dade16c553%7C53d82571da1947e49cb4625a166a4a2a%7C0%7C0%7C63806648
>>> 6632283001%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzI
>>> iLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=FshRCpnIoU0b
>>> c38MYnesotcgOV4JT%2FXVOidbDMpAWbc%3D&reserved=0
>>>
>>> I hate selects, just ignores the dependency :(
>>>
>>>    && !GENERIC_ATOMIC64 [=y])
>>
>> I think the existing assumption was that ARCH_RENESAS implied !GENERIC_ATOMIC64. If that is no longer
>> true then please feel free to adjust drivers/iommu/Kconfig to suit.
>>
> IPMMU is not available on Renesas RISCV SoCs, so maybe something like below?

Seems fair to me, especially if it also means hiding a pointless choice 
for a normal interactive config :)

Cheers,
Robin.

> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -283,7 +283,7 @@ config EXYNOS_IOMMU_DEBUG
> 
>   config IPMMU_VMSA
>          bool "Renesas VMSA-compatible IPMMU"
> -       depends on ARCH_RENESAS || (COMPILE_TEST && !GENERIC_ATOMIC64)
> +       depends on (ARCH_RENESAS && !RISCV) || (COMPILE_TEST && !GENERIC_ATOMIC64)
>          select IOMMU_API
>          select IOMMU_IO_PGTABLE_LPAE
>          select ARM_DMA_USE_IOMMU
> 
> Cheers,
> Prabhakar