Hi James,
On 8/22/25 16:30, James Morse 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 have fields
> indicating support for long counters. As of now, a 44 bit counter
> represented by HAS_LONG field (bit 30) and a 63 bit counter represented
> by LWD (bit 29) can be optionally integrated. Probe for these counters
> and set corresponding feature bits if any of these counters are present.
>
> Signed-off-by: Rohit Mathew <rohit.mathew@xxxxxxx>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> ---
> drivers/resctrl/mpam_devices.c | 23 ++++++++++++++++++++++-
> drivers/resctrl/mpam_internal.h | 8 ++++++++
> 2 files changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 11be34b54643..2ab7f127baaa 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -870,7 +870,7 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> pr_err_once("Counters are not usable because not-ready timeout was not provided by firmware.");
> }
> if (FIELD_GET(MPAMF_MSMON_IDR_MSMON_MBWU, msmon_features)) {
> - bool hw_managed;
> + bool has_long, hw_managed;
> u32 mbwumonidr = mpam_read_partsel_reg(msc, MBWUMON_IDR);
nit: the variable name would be more readable with an underscore,
mwumon_idr.
>
> props->num_mbwu_mon = FIELD_GET(MPAMF_MBWUMON_IDR_NUM_MON, mbwumonidr);
> @@ -880,6 +880,27 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> if (FIELD_GET(MPAMF_MBWUMON_IDR_HAS_RWBW, mbwumonidr))
> mpam_set_feature(mpam_feat_msmon_mbwu_rwbw, props);
>
> + /*
> + * Treat long counter and its extension, lwd as mutually
> + * exclusive feature bits. Though these are dependent
> + * fields at the implementation level, there would never
> + * be a need for mpam_feat_msmon_mbwu_44counter (long
> + * counter) and mpam_feat_msmon_mbwu_63counter (lwd)
> + * bits to be set together.
> + *
> + * mpam_feat_msmon_mbwu isn't treated as an exclusive
> + * bit as this feature bit would be used as the "front
> + * facing feature bit" for any checks related to mbwu
> + * monitors.
> + */
> + has_long = FIELD_GET(MPAMF_MBWUMON_IDR_HAS_LONG, mbwumonidr);
> + if (props->num_mbwu_mon && has_long) {
> + if (FIELD_GET(MPAMF_MBWUMON_IDR_LWD, mbwumonidr))
> + mpam_set_feature(mpam_feat_msmon_mbwu_63counter, props);
> + else
> + mpam_set_feature(mpam_feat_msmon_mbwu_44counter, props);
> + }
> +
> /* Is NRDY hardware managed? */
> mpam_mon_sel_outer_lock(msc);
> hw_managed = mpam_ris_hw_probe_hw_nrdy(ris, MBWU);
> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
> index 9a50a5432f4a..9f627b5f72a1 100644
> --- a/drivers/resctrl/mpam_internal.h
> +++ b/drivers/resctrl/mpam_internal.h
> @@ -178,7 +178,15 @@ enum mpam_device_features {
> mpam_feat_msmon_csu,
> mpam_feat_msmon_csu_capture,
> mpam_feat_msmon_csu_hw_nrdy,
> +
> + /*
> + * Having mpam_feat_msmon_mbwu set doesn't mean the regular 31 bit MBWU
> + * counter would be used. The exact counter used is decided based on the
> + * status of mpam_feat_msmon_mbwu_l/mpam_feat_msmon_mbwu_lwd as well.
mpam_feat_msmon_mbwu_44counter/mpam_feat_msmon_mbwu_63counter
> + */
> mpam_feat_msmon_mbwu,
> + mpam_feat_msmon_mbwu_44counter,
> + mpam_feat_msmon_mbwu_63counter,
> mpam_feat_msmon_mbwu_capture,
> mpam_feat_msmon_mbwu_rwbw,
> mpam_feat_msmon_mbwu_hw_nrdy,
Other than the two nits, the change looks good to me.
Reviewed-by: Ben Horgan <ben.horgan@xxxxxxx>
Thanks,
Ben
