usb: fix hub-port pm_runtime_enable() vs runtime pm transitions
authorDan Williams <dan.j.williams@intel.com>
Tue, 17 Jun 2014 23:16:32 +0000 (16:16 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 18 Jun 2014 00:04:39 +0000 (17:04 -0700)
commite3d105055525d9ea9f8e9cb0db8237df3df1bb9f
tree37448f1ac032726d1e290124734a6a7a067d095d
parent6c79fe4afcb0450bd638f6e959e512aad270ff2f
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>
drivers/usb/core/hub.c
drivers/usb/core/hub.h
drivers/usb/core/port.c