Re: [PATCH v3 05/28] bus: simple-pm-bus: Populate child nodes at probe

On Fri, Jun 13, 2025 at 03:47:45PM +0200, Herve Codina wrote:

The simple-pm-bus driver handles several simple busses. When it is used
with busses other than a compatible "simple-pm-bus", it doesn't populate
its child devices during its probe.

This confuses fw_devlink and results in wrong or missing devlinks.

Once a driver is bound to a device and the probe() has been called,
device_links_driver_bound() is called.

This function performs operation based on the following assumption:
    If a child firmware node of the bound device is not added as a
    device, it will never be added.

Among operations done on fw_devlinks of those "never be added" devices,
device_links_driver_bound() changes their supplier.

With devices attached to a simple-bus compatible device, this change
leads to wrong devlinks where supplier of devices points to the device
parent (i.e. simple-bus compatible device) instead of the device itself
(i.e. simple-bus child).

When the device attached to the simple-bus is removed, because devlinks
are not correct, its consumers are not removed first.

In order to have correct devlinks created, make the simple-pm-bus driver
compliant with the devlink assumption and create its child devices
during its probe.

...

 	if (match && match->data) {
 		if (of_property_match_string(np, "compatible", match->compatible) == 0)
-			return 0;
+			goto populate;
 		else
 			return -ENODEV;
 	}

A nit: seems that now we don't need to keep a symmetry in the branches and
hence the redundant 'else' can be dropped

		if (of_property_match_string(np, "compatible", match->compatible) != 0)
			return -ENODEV;
		goto populate;
	}

But this might be out of the scope here and can be done later on. In my opinion
it will make code slightly easier to follow.


-- 
With Best Regards,
Andy Shevchenko