firmware: arm_scmi: Harden clock parents discovery

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>
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260508153300.2224715-9-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>

diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
index c9b62edce4fdcd16f37eb78edce8f0631feb6f0b..d07cfef243fd3916318cb09a00711728763df7c7 100644 (file)
--- 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;
 }