Re: [PATCH v2 09/45] arm64: mpam: Advertise the CPUs MPAM limits to the driver

Jonathan Cameron
2026-01-05T17:08:56Z

On Fri, 19 Dec 2025 18:11:11 +0000
Ben Horgan <ben.horgan@arm.com> wrote:

> From: James Morse <james.morse@arm.com>
>
> Requestors need to populate the MPAM fields for any traffic they send on
> the interconnect. For the CPUs these values are taken from the
> corresponding MPAMy_ELx register. Each requestor may have a limit on the
> largest PARTID or PMG value that can be used. The MPAM driver has to
> determine the system-wide minimum supported PARTID and PMG values.
>
> To do this, the driver needs to be told what each requestor's limit is.
>
> CPUs are special, but this infrastructure is also needed for the SMMU and
> GIC ITS. Call the helper to tell the MPAM driver what the CPUs can do.
>
> The return value can be ignored by the arch code as it runs well before the
> MPAM driver starts probing.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>