[PATCH] Avoid delay when inializing USB peripheral by dwc2

João Loureiro joaofl at gmail.com
Wed Mar 17 16:19:37 CET 2021

When `usb start` is called on the terminal, the dwc2 driver will try to start every USB device as host first, even if it is explicitly configured as peripheral in the device tree (`dr_mode = "peripheral"`).

So to avoid am unwanted 15 seconds delay when initializing the usb (one second per channel = 1s x 15), this patch adds a check to the initialization, and will skip host initialization of the device is explicitly set as peripheral. The checking is already and correctly done similarly in the `drivers/usb/gadget/dwc2_udc_otg.c` driver.

Signed-off-by: João Loureiro <joaofl at gmail.com>
 drivers/usb/host/dwc2.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index ec643e9f45..7990060f3c 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -21,6 +21,7 @@
 #include <asm/io.h>
 #include <dm/device_compat.h>
 #include <linux/delay.h>
+#include <linux/usb/otg.h>
 #include <power/regulator.h>
 #include <reset.h>
@@ -1204,7 +1205,13 @@ static int dwc2_init_common(struct udevice *dev, struct dwc2_priv *priv)
-	dwc_otg_core_host_init(dev, regs);
+	if (usb_get_dr_mode(dev_ofnode(dev)) == USB_DR_MODE_PERIPHERAL) {
+		dev_dbg(dev, "USB device %s dr_mode set to %d. Skipping host_init.\n",\
+			dev->name, usb_get_dr_mode(dev_ofnode(dev)));
+	} else {
+		dwc_otg_core_host_init(dev, regs);
+	}
 	clrsetbits_le32(&regs->hprt0, DWC2_HPRT0_PRTENA |

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