Re: [PATCH v9 12/13] powercap: arm_scmi: Add get_power_uw to synthetic node

[Sudeep Holla <sudeep.holla@kernel.org>]

On Wed, Sep 09, 2026 at 10:04:36PM +0000, Philip Radford wrote:
> Exposes the current power usage from the immediate children of the
> synthetic (root) powercap node. Iterates over pr->spzones and sums per-zone
> power.
> 
> Signed-off-by: Philip Radford <philip.radford@arm.com>
> ---
> V8->V9
> - Removed redundant if (!pr) check from instance_root_get_power_uw()
> - Stopped returning a partial sum if one child read fails
> ---
>  drivers/powercap/arm_scmi_powercap.c | 34 ++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/powercap/arm_scmi_powercap.c b/drivers/powercap/arm_scmi_powercap.c
> index b5397d7675e6..aac0b00490b2 100644
> --- a/drivers/powercap/arm_scmi_powercap.c
> +++ b/drivers/powercap/arm_scmi_powercap.c
> @@ -17,6 +17,9 @@
>  #define to_scmi_powercap_zone(z)		\
>  	container_of(z, struct scmi_powercap_zone, zone)
>  
> +#define to_scmi_powercap_root(z)		\
> +	container_of(z, struct scmi_powercap_root, instance_root.zone)
> +
>  static const struct scmi_powercap_proto_ops *powercap_ops;
>  
>  struct scmi_powercap_zone {
> @@ -453,9 +456,36 @@ static int instance_root_release(struct powercap_zone *pz)
>  	return 0;
>  }
>  
> -static int instance_root_get_power_uw(struct powercap_zone *pz, u64 *v)
> +static int instance_root_get_power_uw(struct powercap_zone *pz, u64 *power_uw)
>  {
> -	*v = 0;
> +	struct scmi_powercap_root *pr = to_scmi_powercap_root(pz);
> +	struct scmi_powercap_zone *child;
> +
> +	u64 p, acc = 0;
> +	int i, ret;
> +
> +	if (!pz || !power_uw)
> +		return -EINVAL;
> +
> +	for (i = 0; i < pr->num_zones; i++) {
> +		child = &pr->spzones[i];
> +
> +		if (!child->registered || child->invalid)
> +			continue;
> +
> +		if (child->info->parent_id != SCMI_POWERCAP_ROOT_ZONE_ID)
> +			continue;
> +
> +		ret = scmi_powercap_get_power_uw(&child->zone, &p);

Should we skip domains without monitoring here as scmi_powercap_get_power_uw()
return -EINVAL for such domains always ? If the system has one such node, you
will always return error here ?

-- 
Regards,
Sudeep