Re: [PATCH v6 38/40] arm_mpam: Add workaround for T241-MPAM-6

[Gavin Shan]

On 3/14/26 12:46 AM, Ben Horgan wrote:
> From: Shanker Donthineni <sdonthineni@xxxxxxxxxx>
>
> The registers MSMON_MBWU_L and MSMON_MBWU return the number of requests
> rather than the number of bytes transferred.
>
> Bandwidth resource monitoring is performed at the last level cache, where
> each request arrive in 64Byte granularity. The current implementation
> returns the number of transactions received at the last level cache but
> does not provide the value in bytes. Scaling by 64 gives an accurate byte
> count to match the MPAM specification for the MSMON_MBWU and MSMON_MBWU_L
> registers. This patch fixes the issue by reporting the actual number of
> bytes instead of the number of transactions from __ris_msmon_read().
>
> Tested-by: Gavin Shan <gshan@xxxxxxxxxx>
> Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> Reviewed-by: Zeng Heng <zengheng4@xxxxxxxxxx>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> Signed-off-by: Shanker Donthineni <sdonthineni@xxxxxxxxxx>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
> ---
> Changes since rfc:
> MPAM_IIDR_NVIDIA_T421 -> MPAM_IIDR_NVIDIA_T241
> Don't apply workaround to MSMON_MBWU_LWD
> ---
>   Documentation/arch/arm64/silicon-errata.rst |  2 ++
>   drivers/resctrl/mpam_devices.c              | 26 +++++++++++++++++++--
>   drivers/resctrl/mpam_internal.h             |  1 +
>   3 files changed, 27 insertions(+), 2 deletions(-)

Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>