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* [PATCH] Revert "of: property: fw_devlink: Add support for remote-endpoint"
@ 2021-09-27 20:48 Dmitry Baryshkov
  2021-09-27 21:58 ` Saravana Kannan
  0 siblings, 1 reply; 9+ messages in thread
From: Dmitry Baryshkov @ 2021-09-27 20:48 UTC (permalink / raw)
  To: Rob Herring, Frank Rowand, Greg Kroah-Hartman
  Cc: devicetree, linux-kernel, Saravana Kannan

Since the commit f7514a663016 ("of: property: fw_devlink: Add support
for remote-endpoint") Linux kernel started parsing and adding devlinks
for the remote-endpoint properties. However this brings more harm than
good.

For all the remote-endpoints in the graph two links are created. Thus
each and every remote-endpoint ends up in the cyclic graph (instead of
the original intent of catching a cycle of graph + non-graph link):

[    0.381057] OF: remote-endpoint linking /soc@0/geniqup@9c0000/i2c@994000/hdmi-bridge@2b to /soc@0/mdss@ae00000/dsi@ae94000/ports/port@1/endpoint
[    0.394421] OF: remote-endpoint linking /soc@0/geniqup@9c0000/i2c@994000/hdmi-bridge@2b to /hdmi-out/port/endpoint
[    0.407007] OF: remote-endpoint linking /soc@0/phy@88e9000 to /soc@0/spmi@c440000/pmic@2/pmic-tcpm/connector/ports/port@0/endpoint@0
[    0.419648] OF: remote-endpoint linking /soc@0/usb@a6f8800/usb@a600000 to /soc@0/spmi@c440000/pmic@2/pmic-tcpm/ports/port@2/endpoint@0
[    0.432578] OF: remote-endpoint linking /soc@0/cci@ac4f000/i2c-bus@1/cam1@c0 to /soc@0/camss@ac6a000/ports/port@1/endpoint
[    0.444450] OF: remote-endpoint linking /soc@0/camss@ac6a000 to /soc@0/cci@ac4f000/i2c-bus@1/cam1@c0/port/endpoint
[    0.455292] OF: remote-endpoint linking /soc@0/mdss@ae00000/mdp@ae01000 to /soc@0/mdss@ae00000/dsi@ae94000/ports/port@0/endpoint
[    0.467210] OF: remote-endpoint linking /soc@0/mdss@ae00000/mdp@ae01000 to /soc@0/mdss@ae00000/dsi@ae96000/ports/port@0/endpoint
[    0.479239] OF: remote-endpoint linking /soc@0/mdss@ae00000/dsi@ae94000 to /soc@0/mdss@ae00000/mdp@ae01000/ports/port@0/endpoint
[    0.491147] OF: remote-endpoint linking /soc@0/mdss@ae00000/dsi@ae94000 to /soc@0/geniqup@9c0000/i2c@994000/hdmi-bridge@2b/ports/port@0/endpoint
[    0.504979] OF: remote-endpoint linking /soc@0/spmi@c440000/pmic@2/typec@1500 to /soc@0/spmi@c440000/pmic@2/pmic-tcpm/ports/port@0/endpoint
[    0.517958] OF: remote-endpoint linking /soc@0/spmi@c440000/pmic@2/pdphy@1700 to /soc@0/spmi@c440000/pmic@2/pmic-tcpm/ports/port@1/endpoint
[    0.565326] OF: remote-endpoint linking /hdmi-out to /soc@0/geniqup@9c0000/i2c@994000/hdmi-bridge@2b/ports/port@2/endpoint

Under some conditions the device can become it's own supplier,
preventing this device to be probed at all:

$ ls -l /sys/bus/platform/devices/ae00000.mdss/
lrwxrwxrwx    1 root     root             0 Aug  4 15:13 consumer:platform:ae00000.mdss -> ../../../virtual/devlink/platform:ae00000.mdss--platform:ae00000.mdss

I think that until of_link can be tought to handle bi-directional links
on its own, we should not parse remote-endpoint properties. Thus the
aforementioned commit should be reverted.

Cc: Saravana Kannan <saravanak@google.com>
Fixes: f7514a663016 ("of: property: fw_devlink: Add support for remote-endpoint")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/of/property.c | 47 +++++++++++++++----------------------------
 1 file changed, 16 insertions(+), 31 deletions(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index a3483484a5a2..6aaaf01ef36e 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1056,25 +1056,6 @@ 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
@@ -1098,11 +1079,25 @@ 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.
 	 */
-	sup_np = of_get_compat_node(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);
+	}
+
 	if (!sup_np) {
 		pr_debug("Not linking %pOFP to %pOFP - No device\n",
 			 con_np, tmp_np);
@@ -1249,7 +1244,6 @@ static struct device_node *parse_##fname(struct device_node *np,	     \
  * @parse_prop.index: For properties holding a list of phandles, this is the
  *		      index into the list
  * @optional: Describes whether a supplier is mandatory or not
- * @node_not_dev: The consumer node containing the property is never a device.
  *
  * Returns:
  * parse_prop() return values are
@@ -1261,7 +1255,6 @@ 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")
@@ -1286,7 +1279,6 @@ 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_SIMPLE_PROP(pwms, "pwms", "#pwm-cells")
 DEFINE_SIMPLE_PROP(resets, "resets", "#reset-cells")
 DEFINE_SIMPLE_PROP(leds, "leds", NULL)
@@ -1374,7 +1366,6 @@ 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_pwms, },
 	{ .parse_prop = parse_resets, },
 	{ .parse_prop = parse_leds, },
@@ -1421,16 +1412,10 @@ 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_dev_np, phandle);
+			of_link_to_phandle(con_np, phandle);
 			of_node_put(phandle);
-			of_node_put(con_dev_np);
 		}
 		s++;
 	}
-- 
2.33.0


^ permalink raw reply related	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2021-10-06  0:22 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-27 20:48 [PATCH] Revert "of: property: fw_devlink: Add support for remote-endpoint" Dmitry Baryshkov
2021-09-27 21:58 ` Saravana Kannan
2021-09-28  0:56   ` Dmitry Baryshkov
2021-09-28  1:13     ` Saravana Kannan
2021-09-28 12:30       ` Greg Kroah-Hartman
2021-09-28 16:37         ` Saravana Kannan
2021-10-02  1:04       ` Dmitry Baryshkov
2021-10-02  1:21         ` Saravana Kannan
2021-10-06  0:21         ` Saravana Kannan

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