[PATCH v2] clk: scmi: Fix children encountered before parents case

[Sascha Hauer]

When it comes to clocks with parents the SCMI clk driver assumes that
parents are always initialized before their children which might not
always be the case.

During initialization of the parent_data array we have:

	sclk->parent_data[i].hw = hws[sclk->info->parents[i]];

hws[sclk->info->parents[i]] will not yet be initialized when children
are encountered before their possible parents. Solve this by allocating
all struct scmi_clk as an array first and populating all hws[] upfront.

Fixes: 65a8a3dd3b95f ("clk: scmi: Add support for clock {set,get}_parent")
Reviewed-by: peng.fan at nxp.com
Reviewed-by: Cristian Marussi <cristian.marussi at arm.com>
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
Changes in v2:
- Collect reviewed-by from Cristian Marussi and Peng Fan
- Do not use a local variable that is only used once (Christian)
- Link to v1: https://lore.kernel.org/r/20250604-clk-scmi-children-parent-fix-v1-1-be206954d866@pengutronix.de
---
 drivers/clk/clk-scmi.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index 15510c2ff21c0335f5cb30677343bd4ef59c0738..1b1561c84127b9e41bfb6096ceb3626f32c4fee0 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -404,6 +404,7 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
 	const struct scmi_handle *handle = sdev->handle;
 	struct scmi_protocol_handle *ph;
 	const struct clk_ops *scmi_clk_ops_db[SCMI_MAX_CLK_OPS] = {};
+	struct scmi_clk *sclks;
 
 	if (!handle)
 		return -ENODEV;
@@ -430,18 +431,21 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
 	transport_is_atomic = handle->is_transport_atomic(handle,
 							  &atomic_threshold_us);
 
+	sclks = devm_kcalloc(dev, count, sizeof(*sclks), GFP_KERNEL);
+	if (!sclks)
+		return -ENOMEM;
+
+	for (idx = 0; idx < count; idx++)
+		hws[idx] = &sclks[idx].hw;
+
 	for (idx = 0; idx < count; idx++) {
-		struct scmi_clk *sclk;
+		struct scmi_clk *sclk = &sclks[idx];
 		const struct clk_ops *scmi_ops;
 
-		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
-		if (!sclk)
-			return -ENOMEM;
-
 		sclk->info = scmi_proto_clk_ops->info_get(ph, idx);
 		if (!sclk->info) {
 			dev_dbg(dev, "invalid clock info for idx %d\n", idx);
-			devm_kfree(dev, sclk);
+			hws[idx] = NULL;
 			continue;
 		}
 
@@ -479,13 +483,11 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
 		if (err) {
 			dev_err(dev, "failed to register clock %d\n", idx);
 			devm_kfree(dev, sclk->parent_data);
-			devm_kfree(dev, sclk);
 			hws[idx] = NULL;
 		} else {
 			dev_dbg(dev, "Registered clock:%s%s\n",
 				sclk->info->name,
 				scmi_ops->enable ? " (atomic ops)" : "");
-			hws[idx] = &sclk->hw;
 		}
 	}
 

---
base-commit: 5abc7438f1e9d62e91ad775cc83c9594c48d2282
change-id: 20250604-clk-scmi-children-parent-fix-45a8912b8ba0

Best regards,
-- 
Sascha Hauer <s.hauer at pengutronix.de>