usb: fix hub-port pm_runtime_enable() vs runtime pm transitions

Commit 9262c19d14c4 "usb: disable port power control if not supported in
wHubCharacteristics" gated enabling runtime pm for usb_port devices on
whether the parent hub supports power control, which causes a
regression.  The port must still be allowed to carry out runtime pm
callbacks and receive a -EAGAIN or -EBUSY result.  Otherwise the
usb_port device will transition to the pm error state and trigger the
same for the child usb_device.

Prior to the offending commit usb_hub_create_port_device() arranged for
runtime pm to be disabled is dev_pm_qos_expose_flags() failed.  Instead,
force the default state of PM_QOS_FLAG_NO_POWER_OFF flag to be set prior
to enabling runtime pm.  If that policy can not be set then fail
registration.

Report: http://marc.info/?l=linux-usb&m=140290586301336&w=2
Fixes: 9262c19d14c4 ("usb: disable port power control if not supported in wHubCharacteristics")
Reported-by: Bjørn Mork <bjorn@mork.no>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 78c3cd20d7ae..21b99b4b4082 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1577,6 +1577,12 @@ static int hub_configure(struct usb_hub *hub,
                 }
         }
         hdev->maxchild = i;
+        for (i = 0; i < hdev->maxchild; i++) {
+                struct usb_port *port_dev = hub->ports[i];
+
+                pm_runtime_put(&port_dev->dev);
+        }
+
         mutex_unlock(&usb_port_peer_mutex);
         if (ret < 0)
                 goto fail;