[PATCH v2] phy: can-transceiver: Re-instate "mux-states" property presence check

[Geert Uytterhoeven]

On the Renesas Gray Hawk Single development board:

    can-transceiver-phy can-phy0: /can-phy0: failed to get mux-state (0)

"mux-states" is an optional property for CAN transceivers.  However,
mux_get() always prints an error message in case of an error, including
when the property is not present, confusing the user.

Fix this by re-instating the property presence check (this time using
the proper API) in a wrapper around devm_mux_state_get().  When the
multiplexer subsystem gains support for optional muxes, the wrapper can
just be removed.

In addition, propagate all real errors upstream, instead of ignoring
them.

Fixes: d02dfd4ceb2e9f34 ("phy: can-transceiver: Drop unnecessary "mux-states" property presence check")
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
Alternatively, the multiplexer subsystem needs to gain support for
getting an optional mux...

v2:
  - Add and use devm_mux_state_get_optional(),
  - No given tags added, as the new solution is different.
---
 drivers/phy/phy-can-transceiver.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
index 2bec70615449f94d..f59caff4b3d4c267 100644
--- a/drivers/phy/phy-can-transceiver.c
+++ b/drivers/phy/phy-can-transceiver.c
@@ -93,6 +93,16 @@ static const struct of_device_id can_transceiver_phy_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
 
+/* Temporary wrapper until the multiplexer subsystem supports optional muxes */
+static inline struct mux_state *
+devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+{
+	if (!of_property_present(dev->of_node, "mux-states"))
+		return NULL;
+
+	return devm_mux_state_get(dev, mux_name);
+}
+
 static int can_transceiver_phy_probe(struct platform_device *pdev)
 {
 	struct phy_provider *phy_provider;
@@ -114,13 +124,11 @@ static int can_transceiver_phy_probe(struct platform_device *pdev)
 	match = of_match_node(can_transceiver_phy_ids, pdev->dev.of_node);
 	drvdata = match->data;
 
-	mux_state = devm_mux_state_get(dev, NULL);
-	if (IS_ERR(mux_state)) {
-		if (PTR_ERR(mux_state) == -EPROBE_DEFER)
-			return PTR_ERR(mux_state);
-	} else {
-		can_transceiver_phy->mux_state = mux_state;
-	}
+	mux_state = devm_mux_state_get_optional(dev, NULL);
+	if (IS_ERR(mux_state))
+		return PTR_ERR(mux_state);
+
+	can_transceiver_phy->mux_state = mux_state;
 
 	phy = devm_phy_create(dev, dev->of_node,
 			      &can_transceiver_phy_ops);
-- 
2.43.0