[PATCH] phy: renesas: rcar-gen3-usb2: Ignore missing VBUS regulator

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Commit b6d7dd157763 ("phy: renesas: rcar-gen3-usb2: Add regulator for
OTG VBUS control") introduced support for controlling OTG VBUS through
the regulator framework.

As part of this change, the driver started requesting an exclusive "vbus"
regulator for OTG-capable PHYs with no_adp_ctrl set. The lookup failure
was propagated unconditionally, causing probe to fail on platforms where
no VBUS regulator is described.

On RZ/V2H and RZ/V2N, which do not use a VBUS regulator, this results
in the following error:

    phy_rcar_gen3_usb2 15800200.usb-phy:
    dummy supplies not allowed for exclusive requests (id=vbus)

This failure completely prevents the USB 2.0 interface from initializing.

Fix this by allowing the probe to continue if an external VBUS regulator
is missing. Only propagate the error if the internal vbus-regulator node
is explicitly present, or if the lookup returns -EPROBE_DEFER. For all
other missing regulator errors, gracefully assume no external VBUS
regulator is available and return 0.

Fixes: b6d7dd157763 ("phy: renesas: rcar-gen3-usb2: Add regulator for OTG VBUS control")
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
 drivers/phy/renesas/phy-rcar-gen3-usb2.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/renesas/phy-rcar-gen3-usb2.c b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
index ef38c3b365d4..9ae9975d3255 100644
--- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
+++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
@@ -902,8 +902,17 @@ static int rcar_gen3_phy_usb2_vbus_regulator_get_exclusive_enable(struct rcar_ge
 	int ret;
 
 	channel->vbus = devm_regulator_get_exclusive(dev, "vbus");
-	if (IS_ERR(channel->vbus))
-		return PTR_ERR(channel->vbus);
+	if (IS_ERR(channel->vbus)) {
+		ret = PTR_ERR(channel->vbus);
+		/* If vbus-regulator node was present vbus regulator should be available */
+		if (channel->otg_internal_reg)
+			return ret;
+
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		return 0;
+	}
 
 	if (enable) {
 		ret = regulator_enable(channel->vbus);
-- 
2.54.0