Re: [PATCH v9 09/13] powercap: arm_scmi: Enable multiple constraints support

[Sudeep Holla]

On Wed, Sep 09, 2026 at 10:04:33PM +0000, Philip Radford wrote:
> From: Cristian Marussi <cristian.marussi@xxxxxxx>
> 
> Initialize the domains with all the discovered available constraints,
> making available multiple per-domain constraints when the platform has
> advertised support for multiple concurrent power limits.
> 
> CC: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> CC: linux-pm@xxxxxxxxxxxxxxx
> Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> [Philip: Amended Copyright]
> Signed-off-by: Philip Radford <philip.radford@xxxxxxx>
> ---
> V8->V9
> - Added validation check to make sure powercap domain doesn't have too
> many constraints
> ---
>  drivers/powercap/arm_scmi_powercap.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/powercap/arm_scmi_powercap.c b/drivers/powercap/arm_scmi_powercap.c
> index 2d9370aaaf5d..bcd1ba0bde8c 100644
> --- a/drivers/powercap/arm_scmi_powercap.c
> +++ b/drivers/powercap/arm_scmi_powercap.c
> @@ -2,7 +2,7 @@
>  /*
>   * SCMI Powercap support.
>   *
> - * Copyright (C) 2022 ARM Ltd.
> + * Copyright (C) 2022-2026 ARM Ltd.
>   */
>  
>  #include <linux/device.h>
> @@ -491,7 +491,7 @@ static int scmi_powercap_register_zone(struct scmi_powercap_root *pr,
>  
>  	z = powercap_register_zone(&spz->zone, scmi_top_pcntrl, spz->info->name,
>  				   parent ? &parent->zone : NULL,
> -				   &zone_ops, 1, &constraint_ops);
> +				   &zone_ops, spz->info->num_cpli, &constraint_ops);
>  	if (!IS_ERR(z)) {
>  		spz->height = scmi_powercap_get_zone_height(spz);
>  		spz->registered = true;
> @@ -649,6 +649,13 @@ static int scmi_powercap_probe(struct scmi_device *sdev)
>  		 */
>  		spz->info = powercap_ops->info_get(ph, i);
>  
> +		if (spz->info->num_cpli > MAX_CONSTRAINTS_PER_ZONE) {

Since MAX_CONSTRAINTS_PER_ZONE = 10 and our SCMI f/w can return upto 15,
we may have to warn or clamp it to 10 or both.

-- 
Regards,
Sudeep