Re: [PATCH v3 3/9] firmware: arm_scmi: Convert OF-only paths to generic fwnode in SCMI core

On Wed, 2 Sep 2026 14:39:31 +0100
Sudeep Holla [off-list ref] wrote:

On Mon, Aug 24, 2026 at 10:39:29AM -0700, Jonathan Cameron wrote:

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On Thu, 13 Aug 2026 12:32:58 +0100
Sudeep Holla [off-list ref] wrote:
  

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Switch SCMI core plumbing from struct device_node * to struct
fwnode_handle * so the core can describe SCMI instances and protocols using
firmware nodes rather than OF nodes directly.

This change:
  - Replaces core OF property lookups with fwnode_property_*() helpers.
  - Switches child enumeration to
    fwnode_for_each_available_child_node_scoped().  

Why the scoped version? See inline for more on this.  Probably just needs
a comment here (or use the non _scoped variant)
  

Sure

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  - Plumbs fwnode through the SCMI device creation and channel setup paths.
  - Updates transport ->chan_available() callbacks to take a fwnode.
  - Stores per-protocol child fwnodes in info->active_protocols so the core
    can later locate the descriptor for a given protocol ID.
  - Updates mailbox/optee/smc/virtio transports to accept fwnodes and map
    back to OF nodes where their existing parsing remains DT-specific.

DT-only transports such as mailbox, OP-TEE and SMC still parse DT
properties by mapping the fwnode back to an OF node. On non-DT systems
these transports report no channel available.

This is a mechanical step towards firmware-node neutrality and prepares the
SCMI core for non-DT transports, such as an ACPI/PCC transport. DT users
continue to work unchanged; no non-DT transport is enabled by this patch.

Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>  

A few minor things - with those cleaned up.  Only the cleanup.h one really
matters.
  

Fixed now.

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Reviewed-by: Jonathan Cameron <redacted>
  

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diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index ef29fd223287..9014723e0f7f 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c  

...
  

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@@ -3352,10 +3354,10 @@ static int scmi_probe(struct platform_device *pdev)
 
 	scmi_enable_matching_quirks(info);
 
-	for_each_available_child_of_node(np, child) {
+	fwnode_for_each_available_child_node_scoped(dev_fwnode(dev), child) {  

There are no early exits yet and I can't see any added later in the series.
So the scoped bit is irrelevant.  I don't mind the change on basis of
hardening or similar but it needs a comment in the patch description to 
justify that.
  

This is mainly to release the reference taken in
fwnode_get_next_available_child_node(). It is taken explicitly via
fwnode_handle_get() before scmi_create_protocol_devices() as discussed
below.

When the loop continues to normal termination the puts are all there
anyway as part of the iterators.  The _scoped case just deals with
early exits via break or return.

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 		u32 prot_id;
 
-		if (of_property_read_u32(child, "reg", &prot_id))
+		if (fwnode_property_read_u32(child, "reg", &prot_id))
 			continue;
 
 		if (!FIELD_FIT(MSG_PROTOCOL_ID_MASK, prot_id)) {