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

Andre Przywara andre.przywara at arm.com
Fri Sep 11 04:28:35 PDT 2026


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 at arm.com>
---
 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




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