Re: [PATCH 07/11] firmware: arm_scmi: Harden clock parents discovery

[Peng Fan <peng.fan@oss.nxp.com>]

On Fri, Feb 27, 2026 at 03:32:21PM +0000, Cristian Marussi wrote:
>Fix clock parents enumeration to account only for effectively discovered
>parents during enumeration, avoiding to trust the total number of parents
>declared upfront by the platform.
>
>Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
>---
> drivers/firmware/arm_scmi/clock.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
>diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
>index d0fb5affb5cf..15faa79abed4 100644
>--- a/drivers/firmware/arm_scmi/clock.c
>+++ b/drivers/firmware/arm_scmi/clock.c
>@@ -270,15 +270,15 @@ static int iter_clk_possible_parents_update_state(struct scmi_iterator_state *st
> 	 * assume it's returned+remaining on first call.
> 	 */
> 	if (!st->max_resources) {
>-		p->clkd->info.num_parents = st->num_returned + st->num_remaining;
>-		p->clkd->info.parents = devm_kcalloc(p->dev,
>-						     p->clkd->info.num_parents,
>+		int num_parents = st->num_returned + st->num_remaining;
>+
>+		p->clkd->info.parents = devm_kcalloc(p->dev, num_parents,
> 						     sizeof(*p->clkd->info.parents),
> 						     GFP_KERNEL);
>-		if (!p->clkd->info.parents) {
>-			p->clkd->info.num_parents = 0;
>+		if (!p->clkd->info.parents)
> 			return -ENOMEM;
>-		}
>+
>+		/* max_resources is used by the iterators to control bounds */
> 		st->max_resources = st->num_returned + st->num_remaining;
> 	}
> 
>@@ -293,9 +293,11 @@ static int iter_clk_possible_parents_process_response(const struct scmi_protocol
> 	const struct scmi_msg_resp_clock_possible_parents *r = response;
> 	struct scmi_clk_ipriv *p = priv;
> 
>-	u32 *parent = &p->clkd->info.parents[st->desc_index + st->loop_idx];
>+	p->clkd->info.parents[st->desc_index + st->loop_idx] =
>+		le32_to_cpu(r->possible_parents[st->loop_idx]);
> 
>-	*parent = le32_to_cpu(r->possible_parents[st->loop_idx]);
>+	/* Count only effectively discovered parents */
>+	p->clkd->info.num_parents++;

It maybe good to give a warning, if mismatch between 
number of effectively discovered parents and "st->num_returned + st->num_remaining"

Anyway this patch LGTM:

Reviewed-by: Peng Fan <peng.fan@nxp.com>

> 
> 	return 0;
> }
>-- 
>2.53.0
>