RE: [PATCH 14/33] arm_mpam: Probe hardware to find the supported partid/pmg values

Shaopeng Tan (Fujitsu)
2025-11-12T07:57:47Z

> From: James Morse <james.morse@arm.com>
>
> CPUs can generate traffic with a range of PARTID and PMG values, but each
> MSC may also have its own maximum size for these fields.
> Before MPAM can be used, the driver needs to probe each RIS on each MSC, to
> find the system-wide smallest value that can be used.
> The limits from requestors (e.g. CPUs) also need taking into account.
>
> While doing this, RIS entries that firmware didn't describe are created under
> MPAM_CLASS_UNKNOWN.
>
> This adds the low level MSC write accessors.
>
> While we're here, implement the mpam_register_requestor() call for the arch
> code to register the CPU limits. Future callers of this will tell us about the
> SMMU and ITS.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Reviewed-by: Ben Horgan <ben.horgan@arm.com>
> Tested-by: Fenghua Yu <fenghuay@nvidia.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
> Tested-by: Peter Newman <peternewman@google.com>
> Signed-off-by: Ben Horgan <ben.horgan@arm.com>
> ---

Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>