This patch implements the mechanism of giveback of URB in
tasklet context, so that hardware interrupt handling time for
usb host controller can be saved much, and HCD interrupt handling
can be simplified.

Motivations:

1), on some arch(such as ARM), DMA mapping/unmapping is a bit
time-consuming, for example: when accessing usb mass storage
via EHCI on pandaboard, the common length of transfer buffer is 120KB,
the time consumed on DMA unmapping may reach hundreds of microseconds;
even on A15 based box, the time is still about scores of microseconds

2), on some arch, reading DMA coherent memoery is very time-consuming,
the most common example is usb video class driver[1]

3), driver's complete() callback may do much things which is driver
specific, so the time is consumed unnecessarily in hardware irq context.

4), running driver's complete() callback in hardware irq context causes
that host controller driver has to release its lock in interrupt handler,
so reacquiring the lock after return may busy wait a while and increase
interrupt handling time. More seriously, releasing the HCD lock makes
HCD becoming quite complicated to deal with introduced races.

So the patch proposes to run giveback of URB in tasklet context, then
time consumed in HCD irq handling doesn't depend on drivers' complete and
DMA mapping/unmapping any more, also we can simplify HCD since the HCD
lock isn't needed to be released during irq handling.

The patch should be reasonable and doable:

1), for drivers, they don't care if the complete() is called in hard irq
context or softirq context

2), the biggest change is the situation in which usb_submit_urb() is called
in complete() callback, so the introduced tasklet schedule delay might be a
con, but it shouldn't be a big deal:

	- control/bulk asynchronous transfer isn't sensitive to schedule
	  delay

	- the patch schedules giveback of periodic URBs using
	  tasklet_hi_schedule, so the introduced delay should be very
	  small

	- for ISOC transfer, generally, drivers submit several URBs
	  concurrently to avoid interrupt delay, so it is OK with the
	  little schedule delay.

	- for interrupt transfer, generally, drivers only submit one URB
	  at the same time, but interrupt transfer is often used in event
	  report, polling, ... situations, and a little delay should be OK.

Considered that HCDs may optimize on submitting URB in complete(), the
patch may cause the optimization not working, so introduces one flag to mark
if the HCD supports to run giveback URB in tasklet context. When all HCDs
are ready, the flag can be removed.

[1], http://marc.info/?t=136438111600010&r=1&w=2

Cc: Oliver Neukum <oliver@neukum.org>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When building the htmldocs (in verbose mode), scripts/kernel-doc reports the
following type of warnings:

Warning(drivers/usb/core/usb.c:76): No description found for return value of
'usb_find_alt_setting'

Fix them by:
- adding some missing descriptions of return values
- using "Return" sections for those descriptions
Signed-off-by: NYacine Belkadi <yacine.belkadi.1@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The hub driver's usb_port_suspend() routine doesn't handle errors
related to Link Power Management properly.  It always returns failure,
it doesn't try to clean up the wakeup setting, (in the case of system
sleep) it doesn't try to go ahead with the port suspend regardless,
and it doesn't try to apply the new power-off mechanism.

This patch fixes these problems.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Acked-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The hub driver is inconsistent in its organization of code for
enabling and disabling remote wakeup.  There is a special routine to
disable wakeup for SuperSpeed devices but not for slower devices, and
there is no special routine to enable wakeup.

This patch refactors the code.  It renames and changes the existing
function to make it handle both SuperSpeed and non-SuperSpeed devices,
and it adds a corresponding routine to enable remote wakeup.  It also
changes the speed determination to look at the device's speed rather
than the speed of the parent hub -- this shouldn't make any difference
because a SuperSpeed device always has to be attached to a SuperSpeed
hub and conversely.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch simplifies the interface presented by usb_get_status().
Instead of forcing callers to check for the proper data length and
convert the status value to host byte order, the function will now
do these things itself.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The USB hub driver's event handler contains a check to catch SuperSpeed
devices that transitioned into the SS.Inactive state and tries to fix
them with a reset. It decides whether to do a plain hub port reset or
call the usb_reset_device() function based on whether there was a device
attached to the port.

However, there are device/hub combinations (found with a JetFlash
Transcend mass storage stick (8564:1000) on the root hub of an Intel
LynxPoint PCH) which can transition to the SS.Inactive state on
disconnect (and stay there long enough for the host to notice). In this
case, above-mentioned reset check will call usb_reset_device() on the
stale device data structure. The kernel will send pointless LPM control
messages to the no longer connected device address and can even cause
several 5 second khubd stalls on some (buggy?) host controllers, before
finally accepting the device's fate amongst a flurry of error messages.

This patch makes the choice of reset dependent on the port status that
has just been read from the hub in addition to the existence of an
in-kernel data structure for the device, and only proceeds with the more
extensive reset if both are valid.
Signed-off-by: NJulius Werner <jwerner@chromium.org>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

For certain (HP) printers the printer device_id does not only contain a
static part identifying the printer, but it also contains a dynamic part
giving printer status, ink level, etc.

To get to this info various userspace utilities need to be able to make a
printer class 'get_device_id' request without first claiming the interface
(as that is in use for the actual printer driver).

Since the printer class 'get_device_id' request does not change interface
settings in anyway, allowing this without claiming the interface should not
cause any issues.

CC: Sanjay Kumar <sanjay.kumar14@hp.com>
CC: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch removes a redundant nested "#ifdef CONFIG_PM" from the hub
driver.  It also adds a label to the "#endif" line corresponding to
the outer "#ifdef CONFIG_PM".
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Control transfers have both IN and OUT (or SETUP) packets, so when
clearing TT buffers for a control transfer it's necessary to send
two HUB_CLEAR_TT_BUFFER requests to the hub.
Signed-off-by: NWilliam Gulland <wgulland@google.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

USB spec stats that short packet can only appear at the end
of transfer. Because lost of HC(EHCI/UHCI/OHCI/...) can't
build a full packet from discontinuous buffers, we introduce
the limit in usb_submit_urb() to avoid such kind of bad sg buffers
coming from driver.

The limit might be a bit strict:
	- platform has iommu to do sg list mapping
	- some host controllers may support to build full packet from
	discontinuous buffers.

But considered that most of HCs don't support that, and driver
need work well or keep consistent on different HCs and ARCHs, we
have to introduce the limit.

Currently, only usbtest is reported to pass such sg buffers to HC,
and other users(mass storage, usbfs) don't have the problem.

We don't check it on USB wireless device, because:
	- wireless devices can't be attached to common USB
	  bus(EHCI/UHCI/OHCI/...)
	- the max packet size of endpoint may be odd, and often can't
	devide 4KB which is a typical usage in usb mass storage application
Reported-by: NKonstantin Filatov <kfilatov@parallels.com>
Reported-by: NDenis V. Lunev <den@openvz.org>
Cc: Felipe Balbi <balbi@ti.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

None of these USB files need idr.h, so don't include it.

Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: NFelipe Balbi <balbi@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The hub driver was recently changed to use "global" suspend for system
suspend transitions on non-SuperSpeed buses.  This means that we don't
suspend devices individually by setting the suspend feature on the
upstream hub port; instead devices all go into suspend automatically
when the root hub stops transmitting packets.  The idea was to save
time and to avoid certain kinds of wakeup races.

Now it turns out that many hubs are buggy; they don't relay wakeup
requests from a downstream port to their upstream port if the
downstream port's suspend feature is not set (depending on the speed
of the downstream port, whether or not the hub is enabled for remote
wakeup, and possibly other factors).

We can't have hubs dropping wakeup requests.  Therefore this patch
goes partway back to the old policy: It sets the suspend feature for a
port if the device attached to that port or any of its descendants is
enabled for wakeup.  People will still be able to benefit from the
time savings if they don't care about wakeup and leave it disabled on
all their devices.

In order to accomplish this, the patch adds a new field to the usb_hub
structure: wakeup_enabled_descendants is a count of how many devices
below a suspended hub are enabled for remote wakeup.  A corresponding
new subroutine determines the number of wakeup-enabled devices at or
below an arbitrary suspended USB device.

This should be applied to the 3.10 stable kernel.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: NToralf Förster <toralf.foerster@gmx.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

usb_hub_to_struct_hub() can return NULL in some unlikely cases.
Add checks where appropriate, or pass the hub pointer as an additional
argument if it's known to be valid.

The places it makes sense to check usb_hub_to_struct_hub()
are picked based on feedback from Alan Stern.
Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There is a misprint in init_usb_class():
IS_ERR is used to get error code instead of PTR_ERR.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: NAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Adds abitilty to tune L1 timeout (inactivity timer for usb2 link sleep)
and BESL (best effort service latency)via sysfs.

This also adds a new usb2_lpm_parameters structure with those variables to
struct usb_device.
Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>

The "runtime idle" helper routine, rpm_idle(), currently ignores
return values from .runtime_idle() callbacks executed by it.
However, it turns out that many subsystems use
pm_generic_runtime_idle() which checks the return value of the
driver's callback and executes pm_runtime_suspend() for the device
unless that value is not 0.  If that logic is moved to rpm_idle()
instead, pm_generic_runtime_idle() can be dropped and its users
will not need any .runtime_idle() callbacks any more.

Moreover, the PCI, SCSI, and SATA subsystems' .runtime_idle()
routines, pci_pm_runtime_idle(), scsi_runtime_idle(), and
ata_port_runtime_idle(), respectively, as well as a few drivers'
ones may be simplified if rpm_idle() calls rpm_suspend() after 0 has
been returned by the .runtime_idle() callback executed by it.

To reduce overall code bloat, make the changes described above.
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: NKevin Hilman <khilman@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NKevin Hilman <khilman@linaro.org>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>

This patch adds Wireless USB root hub support to the USB HCD.  It allows
the HWA to create its root hub which previously failed because the HCD
treated wireless root hubs the same as USB2 high speed hubs.  The creation
of the root hub would fail in that case due to lack of TTs which wireless
root hubs do not support.
Signed-off-by: NThomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Increase the current arbitrary limit for isocronous packet size to a
value large enough to account for USB 3.0 super bandwidth streams,
bMaxBurst (0~15 allowed, 1~16 packets)
bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
so the size max for one USB 3 isocronous transfer is
1024 byte * 16 * 3 = 49152 byte
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NFederico Manzan <f.manzan@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The current EHCI code sleeps a flat 110ms in the resume path if there
was a USB 1.1 device connected to its companion controller during
suspend, waiting for the device to reappear and reset so that it can be
handed back to the companion. This is necessary if the device uses
persist, so that the companion controller can actually see it during its
own resume path.

However, if the device doesn't use persist, this is entirely
unnecessary. We might just as well ignore it and have the normal device
detection/reset/handoff code handle it asynchronously when it eventually
shows up. As USB 1.1 devices are almost exclusively HIDs these days (for
which persist has no value), this can allow distros to shave another
tenth of a second off their resume time.

In order to enable this optimization, the patch also adds a new
usb_for_each_dev() iterator that is exported by the USB core and wraps
bus_for_each_dev() with the logic to differentiate between struct
usb_device and struct usb_interface on the usb_bus_type bus.
Signed-off-by: NJulius Werner <jwerner@chromium.org>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes parenthesis error in sizeof function in Usb/message.c
Signed-off-by: NTülin İzer <tulinizer@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes error: 'no space before bracket' in Usb/message.c
Signed-off-by: NTülin İzer <tulinizer@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes error: 'do not use assignment in if condition'
in USB/devio.c.
Signed-off-by: NTülin İzer <tulinizer@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes error 'Macros with complex values should be enclosed in
parenthesis' in USB/devio.c
Signed-off-by: NTülin İzer <tulinizer@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes warning: 'use <linux/uacces.h> instead <asm/uacces.h>'
found by checkpatch in usb/devio.c.
Signed-off-by: NTülin İzer <tulinizer@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Werner Fink has reported problems with this hub.
Signed-off-by: NOliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 84ebc102 (USB: remove
CONFIG_USB_SUSPEND option) failed to remove all of the usages of
USB_SUSPEND throughout the kernel.  This patch (as1677) removes the
remaining instances of that symbol.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When usbfs receives a ctrl-request from userspace it calls check_ctrlrecip,
which for a request with USB_RECIP_ENDPOINT tries to map this to an interface
to see if this interface is claimed, except for ctrl-requests with a type of
USB_TYPE_VENDOR.

When trying to use this device: http://www.akaipro.com/eiepro
redirected to a Windows vm running on qemu on top of Linux.

The windows driver makes a ctrl-req with USB_TYPE_CLASS and
USB_RECIP_ENDPOINT with index 0, and the mapping of the endpoint (0) to
the interface fails since ep 0 is the ctrl endpoint and thus never is
part of an interface.

This patch fixes this ctrl-req failing by skipping the checkintf call for
USB_RECIP_ENDPOINT ctrl-reqs on the ctrl endpoint.
Reported-by: NDave Stikkolorum <d.r.stikkolorum@hhs.nl>
Tested-by: NDave Stikkolorum <d.r.stikkolorum@hhs.nl>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that devtmpfs is caring about uid/gid, we need to use the correct
internal types so users who have USER_NS enabled will have things work
properly for them.

Thanks to Eric for pointing this out, and the patch review.
Reported-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch removes the depends on USB from all config symbols in
drivers/usb/host/Kconfig and replace that with an if USB / endif block
as suggested by Alan Stern. Some source ... Kconfig lines have been
shuffled around to permit a better regroupment of the Kconfig files
depending on "config USB" item. No functionnal change is introduced.
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Some drivers want to tell userspace what uid and gid should be used for
their device nodes, so allow that information to percolate through the
driver core to userspace in order to make this happen.  This means that
some systems (i.e.  Android and friends) will not need to even run a
udev-like daemon for their device node manager and can just rely in
devtmpfs fully, reducing their footprint even more.
Signed-off-by: NKay Sievers <kay@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove the call to dev_pm_qos_hide_flags(), added by commit 6e30d7cb
"usb: Add driver/usb/core/(port.c,hub.h) files", from
usb_port_device_release(), because (1) it is completely unnecessary
(the flags have been removed already by the PM core during the
unregistration of the device object) and (2) it triggers a NULL
pointer dereference in sysfs_find_dirent() (dev->kobj.sd is NULL at
this point).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

  when suspend, it need check 'udev->actconfig'.
  so when process failure, also need check it.
Signed-off-by: NChen Gang <gang.chen@asianux.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 9214d1d8 set the USB persist flag as a default for all devices.
This might be desirable for some distributions, but it certainly has its
trade-offs... most importantly, it can significantly increase system
resume time, because the kernel blocks on resuming (and sometimes
resetting) USB devices before it unfreezes userspace.

This patch introduces a new config option CONFIG_USB_DEFAULT_PERSIST,
which allows distributions to make this decision on their own without
the need to carry a custom patch or revert the kernel's setting in
userspace.

[edited the Kconfig help text a bit - gregkh]
Signed-off-by: NJulius Werner <jwerner@chromium.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

It seems to be getting more common recently for EHCI host controllers
to be probed after their companion UHCI or OHCI controllers.  This may
be caused partly by splitting the ehci-pci driver out from ehci-hcd,
or it may be caused by changes in the way the kernel does driver
probing.

Regardless, it has a tendency to cause problems.  When an EHCI
controller is initialized, it takes ownership of all the ports away
from the companions.  In effect, it forcefully disconnects all the USB
devices that may already be using a companion controller.

This patch (as1672b) tries to make the transition more orderly by
deconfiguring the root hubs for all the companion controllers before
initializing the EHCI controller, and reconfiguring them afterward.
The result is a soft disconnect rather than a hard one.

Internally, the patch refactors the code involved in associating EHCI
controllers with their companions.  The old approach, in which a
single function is called with an argument telling it what to do (the
companion_action enum), has been replaced with a scheme using multiple
callback functions, each performing a single task.

This patch won't solve all the problems people encounter when their
EHCI controllers start up, but it will at least reduce the number of
error messages generated by the unexpected disconnections.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Tested-by: NJenya Y <jy.gerstmaier@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch (as1675) removes the CONFIG_USB_SUSPEND option, essentially
replacing it everywhere with CONFIG_PM_RUNTIME (except for one place
in hub.c, where it is replaced with CONFIG_PM because the code needs
to be used in both runtime and system PM).  The net result is code
shrinkage and simplification.

There's very little point in keeping CONFIG_USB_SUSPEND because almost
everybody enables it.  The few that don't will find that the usbcore
module has gotten somewhat bigger and they will have to take active
measures if they want to prevent hubs from being runtime suspended.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
CC: Peter Chen <peter.chen@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch (as1674) speeds up system sleep transitions by not
suspending each individual device on a USB-1.1 or USB-2 bus.  The
devices will automatically go into suspend when their root hubs are
suspended (i.e., stop sending out Start-Of-Frame packets) -- this is
what the USB spec calls "global suspend".

Since this is what we do already when CONFIG_USB_SUSPEND isn't
enabled, it shouldn't cause any problems.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
CC: Peter Chen <peter.chen@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch (as1673) reduces the amount of log spew from the hub driver
by removing a bunch of error messages in the case where the device in
question is already known to have been disconnected.  Since the
disconnect event itself appears in the log, there's no need for other
error messages.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Tested-by: NJenya Y <jy.gerstmaier@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The calls to usb_poison_urb and usb_unpoison_urb are expected to be
balanced. However, if an urb that has not yet been submitted is
poisoned, its reject counter will not be increased as its ep-field is
NULL. A consecutive call to unpoison will thus in fact poison the urb
as its reject counter will be decremented to a negative value,
effectively preventing the urb from being submitted.

Note that there are currently no in-kernel drivers affected by this.

Cc: Alan Stern <stern@rowland.harvard.edu>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Return an error if hub->descriptor->bNbrPorts==0. Without this additional
check, we can end up doing a "hub->ports = kzalloc(0, GFP_KERNEL)".
This hub->ports pointer will therefore be non-NULL and will be used.
Example of dmesg:
   INIT: usb 1-1: New USB device found, idVendor=0424, idProduct=2512
   usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
   hub 1-1:1.0: USB hub found
   version 2.86 bootinghub 1-1:1.0: 0 ports detected
   Unable to handle kernel NULL pointer dereference at virtual address 00000010
Signed-off-by: NDavid Linares <dlinares.linux@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch adds comments on interface driver suspend callback
to emphasize that the failure return value is ignored by
USB core in system sleep context, so do not try to recover
device for this case and let resume/reset_resume callback
handle the suspend failure if needed.

Also kerneldoc for usb_suspend_both() is updated with the
fact.
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>