Re: [PATCH v3 08/47] arm64: mpam: Advertise the CPUs MPAM limits to the driver

Catalin Marinas
2026-01-15T18:16:57Z

On Mon, Jan 12, 2026 at 04:58:35PM +0000, Ben Horgan 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.
>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> Signed-off-by: Ben Horgan <ben.horgan@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>