[PATCH] usb: xhci: dbc: Don't decrement runtime PM counter if DBC is not started

[PATCH] usb: xhci: dbc: Don't decrement runtime PM counter if DBC is not started

[Kai-Heng Feng]

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.feng@canonical.com>
---
 drivers/usb/host/xhci-dbgcap.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index 1fbfd89d0a0f..387f124a8334 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -508,16 +508,18 @@ static int xhci_do_dbc_start(struct xhci_hcd *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)
@@ -544,6 +546,7 @@ static int xhci_dbc_start(struct xhci_hcd *xhci)
 
 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;
@@ -556,10 +559,11 @@ static void xhci_dbc_stop(struct xhci_hcd *xhci)
 		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
-- 
2.17.0

Re: [PATCH] usb: xhci: dbc: Don't decrement runtime PM counter if DBC is not started

[Mathias Nyman]

On 25.06.2018 08:20, Kai-Heng Feng wrote:
> 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.feng@canonical.com>

Thanks, nice catch.
Adding to queue

-Mathias