[PATCH] usb: typec: mux: avoid duplicated mux switches

[Marek Vasut]

Some devices use combo PHYs (i.e. USB3 + DisplayPort), which also
handle the lane muxing. These PHYs are referenced twice from
the USB-C connector (USB super-speed lines and SBU/AUX lines)
resulting in the mux being configured twice. Avoid this by
dropping duplicates.

This is a re-application of b145c3f29d62 ("usb: typec: mux: avoid
duplicated mux switches"), with fix derived from usb: typec: mux:
Fix typec_switch_match() .

Fixes: f576c75f95a5 ("Revert "usb: typec: mux: avoid duplicated mux switches"")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
Co-developed-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
Signed-off-by: Marek Vasut <marex@xxxxxxxxxxxx>
---
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Cc: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx>
Cc: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
Cc: kernel@xxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-usb@xxxxxxxxxxxxxxx
---
- Extensive test by Jens https://lore.kernel.org/all/8bdf6062-8ec2-4c30-8463-0368d3a0f1ce@xxxxxxxxxxxxxxxxxxxxxx/
---
 drivers/usb/typec/mux.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/mux.c b/drivers/usb/typec/mux.c
index 2bc7e8edb3cbd..afa6fc1813978 100644
--- a/drivers/usb/typec/mux.c
+++ b/drivers/usb/typec/mux.c
@@ -277,7 +277,9 @@ static int mux_fwnode_match(struct device *dev, const void *fwnode)
 static void *typec_mux_match(const struct fwnode_handle *fwnode,
 			     const char *id, void *data)
 {
+	struct typec_mux_dev **mux_devs = data;
 	struct device *dev;
+	int i;
 
 	/*
 	 * Device graph (OF graph) does not give any means to identify the
@@ -292,8 +294,18 @@ static void *typec_mux_match(const struct fwnode_handle *fwnode,
 
 	dev = class_find_device(&typec_mux_class, NULL, fwnode,
 				mux_fwnode_match);
+	if (!dev)
+		return ERR_PTR(-EPROBE_DEFER);
 
-	return dev ? to_typec_mux_dev(dev) : ERR_PTR(-EPROBE_DEFER);
+	/* Skip duplicates */
+	for (i = 0; i < TYPEC_MUX_MAX_DEVS; i++)
+		if (to_typec_mux_dev(dev) == mux_devs[i]) {
+			put_device(dev);
+			return NULL;
+		}
+
+
+	return to_typec_mux_dev(dev);
 }
 
 /**
@@ -318,7 +330,8 @@ struct typec_mux *fwnode_typec_mux_get(struct fwnode_handle *fwnode)
 		return ERR_PTR(-ENOMEM);
 
 	count = fwnode_connection_find_matches(fwnode, "mode-switch",
-					       NULL, typec_mux_match,
+					       (void **)mux_devs,
+					       typec_mux_match,
 					       (void **)mux_devs,
 					       ARRAY_SIZE(mux_devs));
 	if (count <= 0) {
-- 
2.53.0