[PATCH 3/9] xhci: Show host status when watchdog triggers and host is assumed dead.

[Mathias Nyman <mathias.nyman@linux.intel.com>]

Additional debugging to show xHC USBSTS register when stop endpoint
command watchdog triggers and host is assumed dead.

useful to know the current status before the controller is stopped by
the xhci driver and everything is released and freed.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-ring.c |  4 ++++
 drivers/usb/host/xhci.h      | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index efcddc0c0991..ba512b25901a 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -955,6 +955,7 @@ void xhci_stop_endpoint_command_watchdog(struct timer_list *t)
 	struct xhci_virt_ep *ep = from_timer(ep, t, stop_cmd_timer);
 	struct xhci_hcd *xhci = ep->xhci;
 	unsigned long flags;
+	u32 usbsts;
 
 	spin_lock_irqsave(&xhci->lock, flags);
 
@@ -965,8 +966,11 @@ void xhci_stop_endpoint_command_watchdog(struct timer_list *t)
 		xhci_dbg(xhci, "Stop EP timer raced with cmd completion, exit");
 		return;
 	}
+	usbsts = readl(&xhci->op_regs->status);
 
 	xhci_warn(xhci, "xHCI host not responding to stop endpoint command.\n");
+	xhci_warn(xhci, "USBSTS:%s\n", xhci_decode_usbsts(usbsts));
+
 	ep->ep_state &= ~EP_STOP_CMD_PENDING;
 
 	xhci_halt(xhci);
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 3ecee10fdcdc..d74f1be26a58 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -2589,6 +2589,35 @@ static inline const char *xhci_decode_portsc(u32 portsc)
 	return str;
 }
 
+static inline const char *xhci_decode_usbsts(u32 usbsts)
+{
+	static char str[256];
+	int ret = 0;
+
+	if (usbsts == ~(u32)0)
+		return " 0xffffffff";
+	if (usbsts & STS_HALT)
+		ret += sprintf(str + ret, " HCHalted");
+	if (usbsts & STS_FATAL)
+		ret += sprintf(str + ret, " HSE");
+	if (usbsts & STS_EINT)
+		ret += sprintf(str + ret, " EINT");
+	if (usbsts & STS_PORT)
+		ret += sprintf(str + ret, " PCD");
+	if (usbsts & STS_SAVE)
+		ret += sprintf(str + ret, " SSS");
+	if (usbsts & STS_RESTORE)
+		ret += sprintf(str + ret, " RSS");
+	if (usbsts & STS_SRE)
+		ret += sprintf(str + ret, " SRE");
+	if (usbsts & STS_CNR)
+		ret += sprintf(str + ret, " CNR");
+	if (usbsts & STS_HCE)
+		ret += sprintf(str + ret, " HCE");
+
+	return str;
+}
+
 static inline const char *xhci_decode_doorbell(u32 slot, u32 doorbell)
 {
 	static char str[256];
-- 
2.17.1