The USB DRD bindingsa at [1] are clear, if not specified the dr_mode property defaults to otg, and this is how Linux behaves.

A cleanup is ongoing on the Linux Device Trees to remove dr_mode when set to "otg", so take this in account and do not fail anymore when dr_mode isn't specified in the glue or dwc3 node.

On the software side, the Linux DWC3 driver behavior defaulting to DR_MODE_OTG is present since v3.12-rc1 added in commit [2].

[1] https://www.kernel.org/doc/Documentation/devicetree/bindings/usb/usb-drd.yam... [2] commit a45c82b84c844 ("usb: dwc3: adapt to use dr_mode device tree helper") https://github.com/torvalds/linux/commit/a45c82b84c844cd85b2ed1aa32596f1bffa...

Reviewed-by: Caleb Connolly caleb.connolly@linaro.org Signed-off-by: Neil Armstrong neil.armstrong@linaro.org --- Changes in v2: - add ref to linux behaviour - Link to v1: https://lore.kernel.org/r/20241016-topic-usb-dwc3-dr-mode-otg-v1-1-4fda56072... --- drivers/usb/dwc3/dwc3-generic.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/dwc3/dwc3-generic.c b/drivers/usb/dwc3/dwc3-generic.c index 2ab41cbae45d78ad140d54e602150b6ddd0a3b99..d62d687ece36d70ccb0f7541eb51c6b7550d932d 100644 --- a/drivers/usb/dwc3/dwc3-generic.c +++ b/drivers/usb/dwc3/dwc3-generic.c @@ -183,10 +183,10 @@ static int dwc3_generic_of_to_plat(struct udevice *dev) /* might be a leaf so check the parent for mode */ node = dev_ofnode(dev->parent); plat->dr_mode = usb_get_dr_mode(node); - if (plat->dr_mode == USB_DR_MODE_UNKNOWN) { - pr_err("Invalid usb mode setup\n"); - return -ENODEV; - } + + /* If none of the nodes have dr_mode, bindings says default is OTG */ + if (!plat->dr_mode) + plat->dr_mode = USB_DR_MODE_OTG; }

return 0; @@ -527,6 +527,10 @@ static int dwc3_glue_bind_common(struct udevice *parent, ofnode node) if (!dr_mode) dr_mode = usb_get_dr_mode(node);

+ /* If none of the nodes have dr_mode, bindings says default is OTG */ + if (!dr_mode) + dr_mode = USB_DR_MODE_OTG; + if (CONFIG_IS_ENABLED(DM_USB_GADGET) && (dr_mode == USB_DR_MODE_PERIPHERAL || dr_mode == USB_DR_MODE_OTG)) { debug("%s: dr_mode: OTG or Peripheral\n", __func__);

--- base-commit: d5cab0d6adc26ec1bbd45c2fed101184d04454ae change-id: 20241016-topic-usb-dwc3-dr-mode-otg-88ec307e0970

Best regards,