[PATCH] usb: dwc3: core: Prevent USB core invalid event buffer address access

[Selvarasu Ganesan]

This commit addresses an issue where the USB core could access an
invalid event buffer address during runtime suspend, potentially causing
SMMU faults and other memory issues. The problem arises from the
following sequence.
	1. In dwc3_gadget_suspend, there is a chance of a timeout when
	moving the USB core to the halt state after clearing the
	run/stop bit by software.
	2. In dwc3_core_exit, the event buffer is cleared regardless of
	the USB core's status, which may lead to an SMMU faults and
	other memory issues. if the USB core tries to access the event
	buffer address.

To prevent this issue, this commit ensures that the event buffer address
is not cleared by software  when the USB core is active during runtime
suspend by checking its status before clearing the buffer address.

Signed-off-by: Selvarasu Ganesan <selvarasu.g@xxxxxxxxxxx>
---
 drivers/usb/dwc3/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index cb82557678dd..c7c1a253862e 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -559,8 +559,10 @@ int dwc3_event_buffers_setup(struct dwc3 *dwc)
 void dwc3_event_buffers_cleanup(struct dwc3 *dwc)
 {
 	struct dwc3_event_buffer	*evt;
+	u32				reg;
 
-	if (!dwc->ev_buf)
+	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+	if (!dwc->ev_buf || !(reg & DWC3_DSTS_DEVCTRLHLT))
 		return;
 
 	evt = dwc->ev_buf;
-- 
2.17.1