Re: [PATCH] MIPS: disable MMID if GINVT is not usable

["Jiaxun Yang" <jiaxun.yang@flygoat.com>]

在2025年6月25日周三 下午2:27，Gregory CLEMENT写道：

Hi Gregory,

> If System-level Interconnect (aka Network on Chip) does not support
> the global invalidation, then MMID feature is not usable. Indeed the
> current implementation of MMID relies on the GINV* instruction.

Yes, it is the case if the NoC IP can't handle AMBA ACE DVM requests.

>
> Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
> ---
>  arch/mips/Kconfig                    | 6 ++++++
>  arch/mips/include/asm/cpu-features.h | 5 ++++-
>  arch/mips/mobileye/Kconfig           | 2 ++
>  3 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 
> 1e48184ecf1ec8e29c0a25de6452ece5da835e30..05ce008459b89f03fa71d94429607feb9d06526f 
> 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -2575,6 +2575,12 @@ config WAR_R10000_LLSC
>  config WAR_MIPS34K_MISSED_ITLB
>  	bool
> 
> +# Some I6500 based SoC do not support the global invalidation on their
> +# System-level Interconnect (aka Network on Chip), this have an
> +# influence on the MMID support.
> +config GINVT_UNSUPPORTED_NOC
> +	bool
> +

I believe this should be a DeviceTree property of CM node instead of Kconfig
hack.

Thanks

-- 
- Jiaxun