[RFC PATCH v10 14/14] acpi: arm64: use MPAM-Fb offset field from ACPI table

From: Andre Przywara

Date: Fri Sep 11 2026 - 07:49:15 EST


The newly introduced mpam_fb_offset field in the MSC node ACPI table holds
the difference between the system-wide MSC ID, as held in the
"Identifier" field, and the ID to be used on the MPAM-Fb protocol level.

Subtract that value from the MSC ID and store that in the mpam_fb_msc_id
property, so that the MPAM-Fb code can correctly address the MSCs.
Previously this field was marked as "must-be-zero", so there would be no
change when using older tables.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
drivers/acpi/arm64/mpam.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/arm64/mpam.c b/drivers/acpi/arm64/mpam.c
index 8c87b4a663439..ee9be310c2184 100644
--- a/drivers/acpi/arm64/mpam.c
+++ b/drivers/acpi/arm64/mpam.c
@@ -257,7 +257,8 @@ static struct platform_device * __init acpi_mpam_parse_msc(struct acpi_mpam_msc_
props[next_prop++] = PROPERTY_ENTRY_U32("pcc-channel",
tbl_msc->base_address);
props[next_prop++] = PROPERTY_ENTRY_U32("mpam-fb-msc-id",
- tbl_msc->identifier);
+ tbl_msc->identifier -
+ tbl_msc->mpam_fb_offset);
}

acpi_mpam_parse_irqs(pdev, tbl_msc, res, &next_res);
--
2.43.0