Commit f7514a66 authored by Saravana Kannan's avatar Saravana Kannan Committed by Greg Kroah-Hartman
Browse files

of: property: fw_devlink: Add support for remote-endpoint 

remote-endpoint property seems to always come in pairs where two devices
point to each other. So, we can't really tell from DT if there is a
functional probe order dependency between these two devices.

However, there can be other dependencies between two devices that point
to each other with remote-endpoint. This non-remote-endpoint dependency
combined with one of the remote-endpoint dependency can lead to a cyclic
dependency[1].

To avoid this cyclic dependency from incorrectly blocking probes,
fw_devlink needs to be made aware of remote-endpoint dependencies even
though remote-endpoint dependencies by themselves won't affect probe
ordering (because fw_devlink will see the cyclic dependency between
remote-endpoint devices and ignore the dependencies that cause the
cycle).

Also, if a device ever needs to know if a non-probe-blocking
remote-endpoint has finished probing, it can now use the sync_state() to
figure it out.

[1] - https://lore.kernel.org/lkml/CAGETcx9Snf23wrXqjDhJiTok9M3GcoVYDSyNYSMj9QnSRrA=cA@mail.gmail.com/#t



Fixes: ea718c69 ("Revert "Revert "driver core: Set fw_devlink=on by default""")
Reported-by: default avatarStephen Boyd <swboyd@chromium.org>
Tested-by: default avatarStephen Boyd <swboyd@chromium.org>
Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210330185056.1022008-1-saravanak@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ed7027fd

drivers/of/property.c

+32 −16
Original line number Diff line number Diff line
@@ -1038,6 +1038,25 @@ static bool of_is_ancestor_of(struct device_node *test_ancestor, 
	return false;

}



static struct device_node *of_get_compat_node(struct device_node *np)

{

	of_node_get(np);



	while (np) {

		if (!of_device_is_available(np)) {

			of_node_put(np);

			np = NULL;

		}



		if (of_find_property(np, "compatible", NULL))

			break;



		np = of_get_next_parent(np);

	}



	return np;

}



/**

 * of_link_to_phandle - Add fwnode link to supplier from supplier phandle

 * @con_np: consumer device tree node
@@ -1061,25 +1080,11 @@ static int of_link_to_phandle(struct device_node *con_np, 
	struct device *sup_dev;

	struct device_node *tmp_np = sup_np;



	of_node_get(sup_np);

	/*

	 * Find the device node that contains the supplier phandle.  It may be

	 * @sup_np or it may be an ancestor of @sup_np.

	 */

	while (sup_np) {



		/* Don't allow linking to a disabled supplier */

		if (!of_device_is_available(sup_np)) {

			of_node_put(sup_np);

			sup_np = NULL;

		}



		if (of_find_property(sup_np, "compatible", NULL))

			break;



		sup_np = of_get_next_parent(sup_np);

	}



	sup_np = of_get_compat_node(sup_np);

	if (!sup_np) {

		pr_debug("Not linking %pOFP to %pOFP - No device\n",

			 con_np, tmp_np);
@@ -1225,6 +1230,8 @@ static struct device_node *parse_##fname(struct device_node *np, \ 
 * @parse_prop.prop_name: Name of property holding a phandle value

 * @parse_prop.index: For properties holding a list of phandles, this is the

 *		      index into the list

 * @optional: The property can be an optional dependency.

 * @node_not_dev: The consumer node containing the property is never a device.

 *

 * Returns:

 * parse_prop() return values are
@@ -1236,6 +1243,7 @@ struct supplier_bindings { 
	struct device_node *(*parse_prop)(struct device_node *np,

					  const char *prop_name, int index);

	bool optional;

	bool node_not_dev;

};



DEFINE_SIMPLE_PROP(clocks, "clocks", "#clock-cells")
@@ -1260,6 +1268,7 @@ DEFINE_SIMPLE_PROP(pinctrl5, "pinctrl-5", NULL) 
DEFINE_SIMPLE_PROP(pinctrl6, "pinctrl-6", NULL)

DEFINE_SIMPLE_PROP(pinctrl7, "pinctrl-7", NULL)

DEFINE_SIMPLE_PROP(pinctrl8, "pinctrl-8", NULL)

DEFINE_SIMPLE_PROP(remote_endpoint, "remote-endpoint", NULL)

DEFINE_SUFFIX_PROP(regulators, "-supply", NULL)

DEFINE_SUFFIX_PROP(gpio, "-gpio", "#gpio-cells")

DEFINE_SUFFIX_PROP(gpios, "-gpios", "#gpio-cells")
@@ -1334,6 +1343,7 @@ static const struct supplier_bindings of_supplier_bindings[] = { 
	{ .parse_prop = parse_pinctrl6, },

	{ .parse_prop = parse_pinctrl7, },

	{ .parse_prop = parse_pinctrl8, },

	{ .parse_prop = parse_remote_endpoint, .node_not_dev = true, },

	{ .parse_prop = parse_gpio_compat, },

	{ .parse_prop = parse_interrupts, },

	{ .parse_prop = parse_regulators, },
@@ -1378,10 +1388,16 @@ static int of_link_property(struct device_node *con_np, const char *prop_name) 
		}



		while ((phandle = s->parse_prop(con_np, prop_name, i))) {

			struct device_node *con_dev_np;



			con_dev_np = s->node_not_dev

					? of_get_compat_node(con_np)

					: of_node_get(con_np);

			matched = true;

			i++;

			of_link_to_phandle(con_np, phandle);

			of_link_to_phandle(con_dev_np, phandle);

			of_node_put(phandle);

			of_node_put(con_dev_np);

		}

		s++;

	}