4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kai-Heng Feng <kai.heng.f...@canonical.com>

[ Upstream commit 74cb319bd97dd62881f97ea5a3228f7c2546bf56 ]

pm_runtime_put_sync() gets called everytime in xhci_dbc_stop().

If dbc is not started, this makes the runtime PM counter incorrectly
becomes 0, and calls autosuspend function. Then we'll keep seeing this:
[54664.762220] xhci_hcd 0000:00:14.0: Root hub is not suspended

So only calls pm_runtime_put_sync() when dbc was started.

Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com>
Signed-off-by: Mathias Nyman <mathias.ny...@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/usb/host/xhci-dbgcap.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -507,16 +507,18 @@ static int xhci_do_dbc_start(struct xhci
        return 0;
 }
 
-static void xhci_do_dbc_stop(struct xhci_hcd *xhci)
+static int xhci_do_dbc_stop(struct xhci_hcd *xhci)
 {
        struct xhci_dbc         *dbc = xhci->dbc;
 
        if (dbc->state == DS_DISABLED)
-               return;
+               return -1;
 
        writel(0, &dbc->regs->control);
        xhci_dbc_mem_cleanup(xhci);
        dbc->state = DS_DISABLED;
+
+       return 0;
 }
 
 static int xhci_dbc_start(struct xhci_hcd *xhci)
@@ -543,6 +545,7 @@ static int xhci_dbc_start(struct xhci_hc
 
 static void xhci_dbc_stop(struct xhci_hcd *xhci)
 {
+       int ret;
        unsigned long           flags;
        struct xhci_dbc         *dbc = xhci->dbc;
        struct dbc_port         *port = &dbc->port;
@@ -555,10 +558,11 @@ static void xhci_dbc_stop(struct xhci_hc
                xhci_dbc_tty_unregister_device(xhci);
 
        spin_lock_irqsave(&dbc->lock, flags);
-       xhci_do_dbc_stop(xhci);
+       ret = xhci_do_dbc_stop(xhci);
        spin_unlock_irqrestore(&dbc->lock, flags);
 
-       pm_runtime_put_sync(xhci_to_hcd(xhci)->self.controller);
+       if (!ret)
+               pm_runtime_put_sync(xhci_to_hcd(xhci)->self.controller);
 }
 
 static void


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