From: Neal Frager neal.frager@amd.com

When the USB3 PHY is not defined in the Linux device tree, there could still be a case where there is a USB3 PHY active on the board and enabled by the first stage bootloader. If serdes clock is being used then the USB will fail to enumerate devices in 2.0 only mode.

To solve this, make sure that the PIPE clock is deselected whenever the USB3 PHY is not defined and guarantees that the USB2 only mode will work in all cases.

Fixes: 9678f3361afc ("usb: dwc3: xilinx: Skip resets and USB3 register settings for USB2.0 mode") Cc: stable@vger.kernel.org Signed-off-by: Neal Frager neal.frager@amd.com Signed-off-by: Radhey Shyam Pandey radhey.shyam.pandey@amd.com Acked-by: Peter Korsgaard peter@korsgaard.com --- Changes for v3: - Modify commit description to drop second "is" and add Peter ack.

Changes for v2: - Add stable@vger.kernel.org in CC. --- drivers/usb/dwc3/dwc3-xilinx.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c index e3738e1610db..a33a42ba0249 100644 --- a/drivers/usb/dwc3/dwc3-xilinx.c +++ b/drivers/usb/dwc3/dwc3-xilinx.c @@ -121,8 +121,11 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data) * in use but the usb3-phy entry is missing from the device tree. * Therefore, skip these operations in this case. */ - if (!priv_data->usb3_phy) + if (!priv_data->usb3_phy) { + /* Deselect the PIPE Clock Select bit in FPD PIPE Clock register */ + writel(PIPE_CLK_DESELECT, priv_data->regs + XLNX_USB_FPD_PIPE_CLK); goto skip_usb3_phy; + }

crst = devm_reset_control_get_exclusive(dev, "usb_crst"); if (IS_ERR(crst)) {