[PATCH 3/8] usb: dwc3: qcom: fix broken non-host-mode suspend

[Johan Hovold <johan+linaro@kernel.org>]

A recent commit implementing wakeup support in host mode instead broke
suspend for peripheral and OTG mode.

The hack that was added in the suspend path to determine the speed of
any device connected to the USB2 bus not only accesses internal driver
data for a child device, but also dereferences a NULL pointer when not
in host mode and there is no HCD.

As the controller can switch role at any time when in OTG mode, there's
no quick fix to this, and since reverting would leave us with broken
suspend in host-mode (wakeup triggers immediately), keep the hack for
now and only fix the NULL-pointer dereference.

Fixes: 6895ea55c385 ("usb: dwc3: qcom: Configure wakeup interrupts during suspend")
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/usb/dwc3/dwc3-qcom.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
index be2e3dd36440..b75ff40f75a2 100644
--- a/drivers/usb/dwc3/dwc3-qcom.c
+++ b/drivers/usb/dwc3/dwc3-qcom.c
@@ -301,8 +301,17 @@ static void dwc3_qcom_interconnect_exit(struct dwc3_qcom *qcom)
 static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom)
 {
 	struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
-	struct usb_hcd *hcd = platform_get_drvdata(dwc->xhci);
 	struct usb_device *udev;
+	struct usb_hcd *hcd;
+
+	if (qcom->mode != USB_DR_MODE_HOST)
+		return USB_SPEED_UNKNOWN;
+
+	/*
+	 * FIXME: Fix this nasty layering violation which currently only
+	 *        "works" in host mode.
+	 */
+	hcd = platform_get_drvdata(dwc->xhci);
 
 	/*
 	 * It is possible to query the speed of all children of
-- 
2.35.1