Re: [PATCH v7 2/9] platform/chrome: cros_ec_typec: Purge blocking switch devlinks

[Andy Shevchenko]

On Thu, Jan 05, 2023 at 09:24:50PM +0800, Pin-yen Lin wrote:
> From: Prashant Malani <pmalani@xxxxxxxxxxxx>
> 
> When using OF graph, the fw_devlink code will create links between the
> individual port driver (cros-ec-typec here) and the parent device for
> a Type-C switch (like mode-switch). Since the mode-switch will in turn
> have the usb-c-connector (i.e the child of the port driver) as a
> supplier, fw_devlink will not be able to resolve the cyclic dependency
> correctly.
> 
> As a result, the mode-switch driver probe() never runs, so mode-switches
> are never registered. Because of that, the port driver probe constantly
> fails with -EPROBE_DEFER, because the Type-C connector class requires all
> switch devices to be registered prior to port registration.
> 
> To break this deadlock and allow the mode-switch registration to occur,
> purge all the usb-c-connector nodes' absent suppliers. This eliminates
> the connector as a supplier for a switch and allows it to be probed.

> Signed-off-by: Prashant Malani <pmalani@xxxxxxxxxxxx>
> 
> Signed-off-by: Pin-yen Lin <treapking@xxxxxxxxxxxx>

Tag block mustn't have the blank line(s).

...

> +	/*
> +	 * OF graph may have set up some device links with switches, since
> +	 * connectors have their own compatible. Purge these to avoid a deadlock
> +	 * in switch probe (the switch mistakenly assumes the connector is a
> +	 * supplier).
> +	 */

Perhaps even

	/*
	 * OF graph may have set up some device links with switches,
	 * since connectors have their own compatible. Purge these
	 * to avoid a deadlock in switch probe (the switch mistakenly
	 * assumes the connector is a supplier).
	 */

?

> +	if (dev->of_node)

I would use if (dev_of_node(dev)), but it's up to you and maintainers.

> +		device_for_each_child_node(dev, fwnode)
> +			fw_devlink_purge_absent_suppliers(fwnode);

-- 
With Best Regards,
Andy Shevchenko