[PATCH v3 08/15] firmware: arm_scmi: Harden clock parents discovery

[Cristian Marussi <cristian.marussi@arm.com>]

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.

Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
v2 --> v3
 - collected Reviewed-by tags
---
 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 c9b62edce4fd..d07cfef243fd 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++;
 
 	return 0;
 }
-- 
2.53.0