[PATCH] usb: dwc3: Look up reference clock DT phandle in both controller DT nodes

[Marek Vasut]

There are currently four disparate placement possibilities of DWC3
reference clock phandle in SoC DTs:
- in top level glue node, with generic subnode without clock (ZynqMP)
- in top level generic node, with no subnode (i.MX8MQ)
- in generic subnode, with other clock in top level node (i.MX8MP)
- in both top level node and generic subnode (Rockchip)

Cover all the possibilities here by looking into both nodes, start
with the top level node as that seems to be used in majority of DTs
to reference the clock.

Signed-off-by: Marek Vasut <marex at denx.de>
---
Cc: Angus Ainslie <angus at akkea.ca>
Cc: Bin Meng <bmeng.cn at gmail.com>
Cc: Fabio Estevam <festevam at gmail.com>
Cc: Kunihiko Hayashi <hayashi.kunihiko at socionext.com>
Cc: Michal Simek <michal.simek at xilinx.com>
Cc: Peng Fan <peng.fan at nxp.com>
Cc: Stefano Babic <sbabic at denx.de>
---
 drivers/usb/dwc3/dwc3-generic.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/usb/dwc3/dwc3-generic.c b/drivers/usb/dwc3/dwc3-generic.c
index 78966718d01..42e92478f25 100644
--- a/drivers/usb/dwc3/dwc3-generic.c
+++ b/drivers/usb/dwc3/dwc3-generic.c
@@ -68,10 +68,27 @@ static int dwc3_generic_probe(struct udevice *dev,
 #if CONFIG_IS_ENABLED(OF_CONTROL)
 	dwc3_of_parse(dwc3);
 
+	/*
+	 * There are currently four disparate placement possibilities of DWC3
+	 * reference clock phandle in SoC DTs:
+	 * - in top level glue node, with generic subnode without clock (ZynqMP)
+	 * - in top level generic node, with no subnode (i.MX8MQ)
+	 * - in generic subnode, with other clock in top level node (i.MX8MP)
+	 * - in both top level node and generic subnode (Rockchip)
+	 * Cover all the possibilities here by looking into both nodes, start
+	 * with the top level node as that seems to be used in majority of DTs
+	 * to reference the clock.
+	 */
 	node = dev_ofnode(dev->parent);
 	index = ofnode_stringlist_search(node, "clock-names", "ref");
 	if (index < 0)
 		index = ofnode_stringlist_search(node, "clock-names", "ref_clk");
+	if (index < 0) {
+		node = dev_ofnode(dev);
+		index = ofnode_stringlist_search(node, "clock-names", "ref");
+		if (index < 0)
+			index = ofnode_stringlist_search(node, "clock-names", "ref_clk");
+	}
 	if (index >= 0)
 		dwc3->ref_clk = &glue->clks.clks[index];
 #endif
-- 
2.35.1