Re: [RFC PATCH 03/38] arm64: mpam: Advertise the CPUs MPAM limits to the driver

Jonathan Cameron
2025-12-18T10:38:50Z

On Fri, 5 Dec 2025 21:58:26 +0000
James Morse <james.morse@arm.com> wrote:

> 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.

Trivial but this commit message line wrap isn't very consistent.

>
> 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>