Re: [PATCH v5 09/12] firmware: arm_scmi: add Powercap MAI get/set support

Cristian Marussi
2026-05-05T20:36:32Z

On Tue, Apr 28, 2026 at 10:09:18AM +0100, Philip Radford wrote:
> Add support for Power Measurement Averaging Interval (MAI)

Hi,

> get and set operations to the SCMI powercap protocol driver.
> Extends scmi_powercap_info to store MAI configuration and
> implement MAI get/set via xfer and optional fast-channel
> support.

You have to stay under 75 chars...ok...but I'd say this commit message
lines are way to short...you can stretch a bit more towards 75chars
without having to split words I think....because

t
o
o

s
h
o
r
t

l
i
n
e
s

are not so good anyway :P

>
> Signed-off-by: Philip Radford <philip.radford@arm.com>
> ---
> drivers/firmware/arm_scmi/powercap.c | 120 +++++++++++++++++++++++++++
> include/linux/scmi_protocol.h | 8 ++
> 2 files changed, 128 insertions(+)
>
> diff --git a/drivers/firmware/arm_scmi/powercap.c b/drivers/firmware/arm_scmi/powercap.c
> index 86262eb0f34a..b5879f204b5e 100644
> --- a/drivers/firmware/arm_scmi/powercap.c
> +++ b/drivers/firmware/arm_scmi/powercap.c
> @@ -401,6 +401,34 @@ scmi_powercap_domain_attrs_process(const struct scmi_protocol_handle *ph,
> dom_info->notify_powercap_measurement_change =
> SUPPORTS_POWERCAP_MEASUREMENTS_CHANGE_NOTIFY(flags);
>
> + if (PROTOCOL_REV_MAJOR(ph->version) >= 0x3) {
> + struct scmi_msg_resp_powercap_domain_attributes_v3 *resp_v3 = r;
> +
> + flags = le32_to_cpu(resp_v3->attributes);
> + if (pinfo->notify_measurements_cmd)
> + dom_info->notify_powercap_measurement_change =
> + SUPPORTS_POWERCAP_MEASUREMENTS_CHANGE_NOTIFY(flags);
> +
> + dom_info->mai_config = SUPPORTS_POWERCAP_MAI_CONFIGURATION(flags);
> + dom_info->min_mai = le32_to_cpu(resp_v3->min_mai);
> + dom_info->max_mai = le32_to_cpu(resp_v3->max_mai);
> + dom_info->mai_step = le32_to_cpu(resp_v3->mai_step);
> +
> + if (dom_info->mai_config) {
> + ret = scmi_powercap_validate(dom_info->min_mai,
> + dom_info->max_mai,
> + dom_info->mai_step,
> + dom_info->mai_config);
> +
> + if (ret) {
> + dev_warn(ph->dev, "Platform reported problem MAI config for domain %d - %s\n",

"....reported invalid MAI config for domain..."

> + dom_info->id, dom_info->name);
> +
> + return ret;
> + }
> + }
> + }
> +
> dom_info->extended_names = SUPPORTS_EXTENDED_NAMES(flags);
>
> dom_info->async_powercap_cap_set =
> @@ -1082,6 +1110,96 @@ static int scmi_powercap_cap_enable_get(const struct scmi_protocol_handle *ph,
> return 0;
> }
>
> +static int scmi_powercap_xfer_mai_get(const struct scmi_protocol_handle *ph, u32 domain_id,
> + u32 *mai)

..bad alignment and till now we try still to stick tpo 80cols in the SCMI
stack if it does NOT really hamper readability...

> +{
> + int ret;
> + struct scmi_xfer *t;
> +
> + ret = ph->xops->xfer_get_init(ph, POWERCAP_MAI_GET, sizeof(u32),
> + sizeof(u32), &t);

...terrible alignment...and you know why :D

> +
> + if (ret)
> + return ret;
> +
> + put_unaligned_le32(domain_id, t->tx.buf);
> +
> + ret = ph->xops->do_xfer(ph, t);
> + if (!ret)
> + *mai = get_unaligned_le32(t->rx.buf);
> +
> + ph->xops->xfer_put(ph, t);
> + return ret;
> +}
> +
> +static int scmi_powercap_xfer_mai_set(const struct scmi_protocol_handle *ph, u32 domain_id, u32 mai)

..same...try to stick to 80 cols when not impossibly ugly..

> +{
> + int ret;
> + struct scmi_xfer *t;
> + struct scmi_msg_powercap_cap_or_pai_set *msg;
> +
> + ret = ph->xops->xfer_get_init(ph, POWERCAP_MAI_SET, sizeof(*msg), 0, &t);

same

> + if (ret)
> + return ret;
> +
> + msg = t->tx.buf;
> + msg->domain_id = cpu_to_le32(domain_id);
> + msg->flags = cpu_to_le32(0);
> + msg->value = cpu_to_le32(mai);
> +
> + ret = ph->xops->do_xfer(ph, t);
> +
> + ph->xops->xfer_put(ph, t);
> + return ret;
> +}
> +
> +static int scmi_powercap_measurements_interval_get(const struct scmi_protocol_handle *ph,
> + u32 domain_id, u32 *val)
> +{

ditto

> + const struct scmi_powercap_info *pc;
> + struct scmi_fc_info *fci;
> +
> + if (!val)
> + return -EINVAL;
> +
> + pc = scmi_powercap_dom_info_get(ph, domain_id);
> + if (!pc)
> + return -EINVAL;
> +
> + fci = pc->cpli[CPL0].fc_info;
> + if (fci && fci[POWERCAP_FC_MAI].get_addr) {
> + *val = ioread32(fci[POWERCAP_FC_MAI].get_addr);
> + trace_scmi_fc_call(SCMI_PROTOCOL_POWERCAP, POWERCAP_MAI_GET, domain_id, 0, *val, 0);
ditto
> + return 0;
> + }
> +
> + return scmi_powercap_xfer_mai_get(ph, domain_id, val);
> +}
> +
> +static int scmi_powercap_measurements_interval_set(const struct scmi_protocol_handle *ph,
> + u32 domain_id, u32 val)
> +{

ditto

> + const struct scmi_powercap_info *pc;
> + struct scmi_fc_info *fci;
> +
> + pc = scmi_powercap_dom_info_get(ph, domain_id);
> + if (!pc)
> + return -EINVAL;
> +
> + if (!pc->mai_config || !val || val < pc->min_mai || val > pc->max_mai)
> + return -EINVAL;
> +
> + fci = pc->cpli[CPL0].fc_info;
> + if (fci && fci[POWERCAP_FC_MAI].set_addr) {
> + iowrite32(val, fci[POWERCAP_FC_MAI].set_addr);
> + ph->hops->fastchannel_db_ring(fci[POWERCAP_FC_MAI].set_db);
> + trace_scmi_fc_call(SCMI_PROTOCOL_POWERCAP, POWERCAP_MAI_SET, domain_id, 0, val, 0);
> + return 0;
> + }
> +
> + return scmi_powercap_xfer_mai_set(ph, domain_id, val);
> +}
> +
> static const struct scmi_powercap_proto_ops powercap_proto_ops = {
> .num_domains_get = scmi_powercap_num_domains_get,
> .info_get = scmi_powercap_dom_info_get,
> @@ -1094,6 +1212,8 @@ static const struct scmi_powercap_proto_ops powercap_proto_ops = {
> .measurements_get = scmi_powercap_measurements_get,
> .measurements_threshold_set = scmi_powercap_measurements_threshold_set,
> .measurements_threshold_get = scmi_powercap_measurements_threshold_get,
> + .measurements_interval_get = scmi_powercap_measurements_interval_get,
> + .measurements_interval_set = scmi_powercap_measurements_interval_set,
> };
>
> static void scmi_powercap_domain_init_fc(const struct scmi_protocol_handle *ph,
> diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> index d0f6c0102559..73d66281dcc3 100644
> --- a/include/linux/scmi_protocol.h
> +++ b/include/linux/scmi_protocol.h
> @@ -675,6 +675,10 @@ struct scmi_powercap_info {
> bool powercap_scale_uw;
> bool extended_names;
> bool fastchannels;
> + bool mai_config;
> + u32 min_mai;
> + u32 max_mai;
> + u32 mai_step;

No docs for new fields ?

> char name[SCMI_MAX_STR_SIZE];
> unsigned int sustainable_power;
> unsigned int accuracy;
> @@ -758,6 +762,10 @@ struct scmi_powercap_proto_ops {
> int (*measurements_threshold_get)(const struct scmi_protocol_handle *ph,
> u32 domain_id, u32 *power_thresh_low,
> u32 *power_thresh_high);
> + int (*measurements_interval_get)(const struct scmi_protocol_handle *ph,
> + u32 domain_id, u32 *val);
> + int (*measurements_interval_set)(const struct scmi_protocol_handle *ph,
> + u32 domain_id, u32 val);

No docs for new fields ?

Thanks,
Cristian