Re: [PATCH v2 05/26] bus: simple-pm-bus: Populate child nodes at probe

Andy Shevchenko
2025-05-08T14:28:08Z

On Wed, May 07, 2025 at 09:12:47AM +0200, Herve Codina wrote:
> The simple-pm-bus drivers handles several simple bus. When it is used

bus --> busses ?

> with busses other than a compatible "simple-pm-bus", it don'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)

Side note, there is an fwnode_is_device_compatible() API for such cases. And IIRC
there is also OF variant of it.

> - return 0;
> + goto populate;
> else
> return -ENODEV;
> }

...

> + if (pdev->dev.of_node)

Why do you need this check? AFAICS it dups the one the call has already in it.

> + of_platform_depopulate(&pdev->dev);

--
With Best Regards,
Andy Shevchenko