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Date: Tue, 30 Mar 2021 11:50:55 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Rob Herring <robh+dt@...nel.org>,
Frank Rowand <frowand.list@...il.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Saravana Kannan <saravanak@...gle.com>
Cc: Stephen Boyd <swboyd@...omium.org>, kernel-team@...roid.com,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1] 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: ea718c699055 ("Revert "Revert "driver core: Set fw_devlink=on by default""")
Reported-by: Stephen Boyd <swboyd@...omium.org>
Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
Rob/Greg,
This needs to go into driver-core due to the Fixes.
-Saravana
drivers/of/property.c | 48 ++++++++++++++++++++++++++++---------------
1 file changed, 32 insertions(+), 16 deletions(-)
diff --git a/drivers/of/property.c b/drivers/of/property.c
index 5036a362f52e..2bb3158c9e43 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -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++;
}
--
2.31.0.291.g576ba9dcdaf-goog
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