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

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Message-ID: <3448db42-cc36-4d2c-b6f9-b2ed85bf9227@redhat.com>
Date: Mon, 10 Nov 2025 09:16:31 +1000
From: Gavin Shan <gshan@...hat.com>
To: Ben Horgan <ben.horgan@....com>, james.morse@....com
Cc: amitsinght@...vell.com, baisheng.gao@...soc.com,
 baolin.wang@...ux.alibaba.com, bobo.shaobowang@...wei.com,
 carl@...amperecomputing.com, catalin.marinas@....com, dakr@...nel.org,
 dave.martin@....com, david@...hat.com, dfustini@...libre.com,
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 jeremy.linton@....com, jonathan.cameron@...wei.com, kobak@...dia.com,
 lcherian@...vell.com, lenb@...nel.org, linux-acpi@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 lpieralisi@...nel.org, peternewman@...gle.com, quic_jiles@...cinc.com,
 rafael@...nel.org, robh@...nel.org, rohit.mathew@....com,
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 tan.shaopeng@...itsu.com, will@...nel.org, xhao@...ux.alibaba.com,
 Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Subject: Re: [PATCH 29/33] arm_mpam: Probe for long/lwd mbwu counters

On 11/7/25 10:34 PM, Ben Horgan wrote:
> From: Rohit Mathew <rohit.mathew@....com>
> 
> 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@....com>
> [ morse: Added 31bit counter feature to simplify later logic ]
> Signed-off-by: James Morse <james.morse@....com>
> Reviewed-by: Ben Horgan <ben.horgan@....com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
> Tested-by: Fenghua Yu <fenghuay@...dia.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Tested-by: Peter Newman <peternewman@...gle.com>
> Signed-off-by: Ben Horgan <ben.horgan@....com>
> ---
> 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@...hat.com>