Re: [PATCH 29/33] arm_mpam: Probe for long/lwd mbwu counters

From: Gavin Shan
Date: Sun Nov 09 2025 - 18:16:56 EST


On 11/7/25 10:34 PM, Ben Horgan wrote:
From: Rohit Mathew <rohit.mathew@xxxxxxx>

mpam v0.1 and versions above v1.0 support optional long counter for
memory bandwidth monitoring. The MPAMF_MBWUMON_IDR register has fields
indicating support for long counters.

Probe these feature bits.

The mpam_feat_msmon_mbwu feature is used to indicate that bandwidth
monitors are supported, instead of muddling this with which size of
bandwidth monitors, add an explicit 31 bit counter feature.

Signed-off-by: Rohit Mathew <rohit.mathew@xxxxxxx>
[ morse: Added 31bit counter feature to simplify later logic ]
Signed-off-by: James Morse <james.morse@xxxxxxx>
Reviewed-by: Ben Horgan <ben.horgan@xxxxxxx>
Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
Tested-by: Fenghua Yu <fenghuay@xxxxxxxxxx>
Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
Tested-by: Peter Newman <peternewman@xxxxxxxxxx>
Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
---
Changes since v3:
Only set the exact counter length that is supported
---
drivers/resctrl/mpam_devices.c | 34 +++++++++++++++++++++------------
drivers/resctrl/mpam_internal.h | 3 +++
2 files changed, 25 insertions(+), 12 deletions(-)


Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>