[PATCH v6 4/5] usb: host: dwc2: force reset assert

Patrick Delaunay patrick.delaunay at st.com
Tue Mar 10 11:09:11 CET 2020

Assert reset before deassert in dwc2_reset;
this patch solve issues when the DWC2 registers are already
initialized with value incompatible with host mode.

Force a hardware reset of the IP reset all the DWC2 registers at
default value, the host driver start with a clean state
(Core Soft reset doen in dwc_otg_core_reset is not enought
 to reset all register).

The error can occurs in U-Boot when DWC2 device gadget driver
force device mode (called by ums or dfu command, before to execute
the usb start command).

Signed-off-by: Patrick Delaunay <patrick.delaunay at st.com>

Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3: None
Changes in v2:
- add clk_disable_bulk in dwc2_usb_remove

 drivers/usb/host/dwc2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index b1b79d0a18..640ae3e730 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -1151,6 +1151,8 @@ static int dwc2_reset(struct udevice *dev)
 			return ret;
+	/* force reset to clear all IP register */
+	reset_assert_bulk(&priv->resets);
 	ret = reset_deassert_bulk(&priv->resets);
 	if (ret) {

More information about the U-Boot mailing list