Commit graph

487 commits

Author SHA1 Message Date
Greg Kroah-Hartman
722b262c96 Merge 4.2-rc4 into usb-next
We want the USB fixes that went into that release in this branch as
well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-07-27 11:15:16 -07:00
Kevin Strasser
655fe4effe usbcore: add sysfs support to xHCI usb3 hardware LPM
Add a sysfs node to make it easier to verify if LPM is supported and being
enabled for USB 3.0 devices.

Signed-off-by: Kevin Strasser <kevin.strasser@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-07-22 15:45:03 -07:00
Lu Baolu
2d2a316765 usb: core: lpm: set lpm_capable for root hub device
Commit 25cd2882e2 ("usb/xhci: Change how we indicate a host supports
Link PM.") removed the code to set lpm_capable for USB 3.0 super-speed
root hub. The intention of that change was to avoid touching usb core
internal field, a.k.a. lpm_capable, and let usb core to set it by
checking U1 and U2 exit latency values in the descriptor.

Usb core checks and sets lpm_capable in hub_port_init(). Unfortunately,
root hub is a special usb device as it has no parent. Hub_port_init()
will never be called for a root hub device. That means lpm_capable will
by no means be set for the root hub. As the result, lpm isn't functional
at all in Linux kernel.

This patch add the code to check and set lpm_capable when registering a
root hub device. It could be back-ported to kernels as old as v3.15,
that contains the Commit 25cd2882e2 ("usb/xhci: Change how we indicate
a host supports Link PM.").

Cc: stable@vger.kernel.org # 3.15
Reported-by: Kevin Strasser <kevin.strasser@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-07-22 14:46:50 -07:00
Robert Schlabbach
fb6d1f7df5 usb: core: Fix USB 3.0 devices lost in NOTATTACHED state after a hub port reset
Fix USB 3.0 devices lost in NOTATTACHED state after a hub port reset.

Dissolve the function hub_port_finish_reset() completely and divide the
actions to be taken into those which need to be done after each reset
attempt and those which need to be done after the full procedure is
complete, and place them in the appropriate places in hub_port_reset().
Also, remove an unneeded forward declaration of hub_port_reset().

Verbose Problem Description:

USB 3.0 devices may be "lost for good" during a hub port reset.
This makes Linux unable to boot from USB 3.0 devices in certain
constellations of host controllers and devices, because the USB device is
lost during initialization, preventing the rootfs from being mounted.

The underlying problem is that in the affected constellations, during the
processing inside hub_port_reset(), the hub link state goes from 0 to
SS.inactive after the initial reset, and back to 0 again only after the
following "warm" reset.

However, hub_port_finish_reset() is called after each reset attempt and
sets the state the connected USB device based on the "preliminary" status
of the hot reset to USB_STATE_NOTATTACHED due to SS.inactive, yet when
the following warm reset is complete and hub_port_finish_reset() is
called again, its call to set the device to USB_STATE_DEFAULT is blocked
by usb_set_device_state() which does not allow taking USB devices out of
USB_STATE_NOTATTACHED state.

Thanks to Alan Stern for guiding me to the proper solution and how to
submit it.

Link: http://lkml.kernel.org/r/trinity-25981484-72a9-4d46-bf17-9c1cf9301a31-1432073240136%20()%203capp-gmx-bs27
Signed-off-by: Robert Schlabbach <robert_s@gmx.net>
Cc: stable <stable@vger.kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-31 15:51:23 +09:00
Greg Kroah-Hartman
d544d273f3 USB: hub.c: move assignment out of if () block
We should not be doing assignments within an if () block
so fix up the code to not do this.

change was created using Coccinelle.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
CC: Dan Williams <dan.j.williams@intel.com>
CC: Petr Mladek <pmladek@suse.cz>
CC: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Felipe Balbi <balbi@ti.com>
2015-05-10 16:01:10 +02:00
Rupesh Tatiya
a842529281 usb: Enable LPM for USB 2.01+ full-speed devices
USB 2.01+ full-speed devices can have extended descriptor as well
and can support LPM.

Signed-off-by: Rupesh Tatiya <rtatiya@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-08 01:43:44 +02:00
Matthew Garrett
58339c2e8b usb: Set unused ports to "fixed" rather than "unknown"
The Microsoft document "Using ACPI to Configure USB Ports on a Computer"
makes it clear that the removable flag will be cleared on ports that are
marked as unused by the firmware. Handle this case to match.

Signed-off-by: Matthew Garrett <mjg59@coreos.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-08 01:43:43 +02:00
Matthew Garrett
92bfbf7135 usb: Prefer firmware values when determining whether a port is removable
Windows appears to pay more attention to the ACPI values than any hub
configuration, so prefer the firmware's opinion on whether a port is
fixed or removable before falling back to the hub values.

Signed-off-by: Matthew Garrett <mjg59@coreos.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-08 01:43:42 +02:00
Felipe Balbi
bbc78c07a5 usb: core: hub: use new USB_RESUME_TIMEOUT
Make sure we're using the new macro, so our
resume signaling will always pass certification.

Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Felipe Balbi <balbi@ti.com>
2015-04-07 12:58:36 -05:00
Linus Torvalds
e29876723f USB patches for 3.20-rc1
Here's the big pull request for the USB driver tree for 3.20-rc1.
 
 Nothing major happening here, just lots of gadget driver updates, new
 device ids, and a bunch of cleanups.
 
 All of these have been in linux-next for a while with no reported
 issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB patches from Greg KH:
 "Here's the big pull request for the USB driver tree for 3.20-rc1.

  Nothing major happening here, just lots of gadget driver updates, new
  device ids, and a bunch of cleanups.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'usb-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (299 commits)
  usb: musb: fix device hotplug behind hub
  usb: dwc2: Fix a bug in reading the endpoint directions from reg.
  staging: emxx_udc: fix the build error
  usb: Retry port status check on resume to work around RH bugs
  Revert "usb: Reset USB-3 devices on USB-3 link bounce"
  uhci-hub: use HUB_CHAR_*
  usb: kconfig: replace PPC_OF with PPC
  ehci-pci: disable for Intel MID platforms (update)
  usb: gadget: Kconfig: use bool instead of boolean
  usb: musb: blackfin: remove incorrect __exit_p()
  USB: fix use-after-free bug in usb_hcd_unlink_urb()
  ehci-pci: disable for Intel MID platforms
  usb: host: pci_quirks: joing string literals
  USB: add flag for HCDs that can't receive wakeup requests (isp1760-hcd)
  USB: usbfs: allow URBs to be reaped after disconnection
  cdc-acm: kill unnecessary messages
  cdc-acm: add sanity checks
  usb: phy: phy-generic: Fix USB PHY gpio reset
  usb: dwc2: fix USB core dependencies
  usb: renesas_usbhs: fix NULL pointer dereference in dma_release_channel()
  ...
2015-02-15 10:24:55 -08:00
Andreas Ruprecht
f6a55884d7 USB / PM: Remove unneeded #ifdef and associated dead code
In commit ceb6c9c862 ("USB / PM: Drop CONFIG_PM_RUNTIME from the
USB core"), all occurrences of CONFIG_PM_RUNTIME in the USB core
code were replaced by CONFIG_PM. This created the following structure
of #ifdef blocks in drivers/usb/core/hub.c:

 [...]
 #ifdef CONFIG_PM
 #ifdef CONFIG_PM
 /* always on / undead */
 #else
 /* dead */
 #endif
 [...]

This patch removes unnecessary inner "#ifdef CONFIG_PM" as well as
the corresponding dead #else block. This inconsistency was found using
the undertaker-checkpatch tool.

Signed-off-by: Andreas Ruprecht <rupran@einserver.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-08 23:42:25 +01:00
Julius Werner
7fa40910e0 usb: Retry port status check on resume to work around RH bugs
The EHCI controller on the RK3288 SoC is violating basic parts of the
USB spec and thereby unable to properly resume a suspended port. It does
not start SOF generation within 3ms of finishing resume signaling, so
the attached device will drop of the bus again. This is a particular
problem with runtime PM, where accessing the device will trigger a
resume that immediately makes it unavailable (and reenumerate with a new
handle).

Thankfully, the persist feature is generally able to work around stuff
like that. Unfortunately, it doesn't quite work in this particular case
because the controller will turn off the CurrentConnectStatus bit for an
instant while the device is reconnecting, which causes the kernel to
conclude that it permanently disappeared. This patch adds a tiny retry
mechanism to the core port resume code which will catch this case and
shouldn't have any notable impact on other controllers.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-03 15:28:32 -08:00
Zhuang Jin Can
7671bd1e97 Revert "usb: Reset USB-3 devices on USB-3 link bounce"
This revert a82b76f7fa.

The commit causes an extra reset in remote wakeup as described in:
http://www.spinics.net/lists/linux-usb/msg119080.html

Signed-off-by: Zhuang Jin Can <jin.can.zhuang@intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-03 15:28:32 -08:00
Deepak Das
fbaecff06a usb: core: hub: modify hub reset logic in hub driver
Currently if port power is turned off by user on hub port
using USBDEVFS then port power is turned back ON
by hub driver.
This commit modifies hub reset logic in hub_port_connect() to prevent
hub driver from turning back the port power ON if port is not owned
by kernel.

Signed-off-by: Deepak Das <deepakdas.linux@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-01-25 21:05:59 +08:00
Alan Stern
524134d422 USB: don't cancel queued resets when unbinding drivers
The USB stack provides a mechanism for drivers to request an
asynchronous device reset (usb_queue_reset_device()).  The mechanism
uses a work item (reset_ws) embedded in the usb_interface structure
used by the driver, and the reset is carried out by a work queue
routine.

The asynchronous reset can race with driver unbinding.  When this
happens, we try to cancel the queued reset before unbinding the
driver, on the theory that the driver won't care about any resets once
it is unbound.

However, thanks to the fact that lockdep now tracks work queue
accesses, this can provoke a lockdep warning in situations where the
device reset causes another interface's driver to be unbound; see

	http://marc.info/?l=linux-usb&m=141893165203776&w=2

for an example.  The reason is that the work routine for reset_ws in
one interface calls cancel_queued_work() for the reset_ws in another
interface.  Lockdep thinks this might lead to a work routine trying to
cancel itself.  The simplest solution is not to cancel queued resets
when unbinding drivers.

This means we now need to acquire a reference to the usb_interface
when queuing a reset_ws work item and to drop the reference when the
work routine finishes.  We also need to make sure that the
usb_interface structure doesn't outlive its parent usb_device; this
means acquiring and dropping a reference when the interface is created
and destroyed.

In addition, cancelling a queued reset can fail (if the device is in
the middle of an earlier reset), and this can cause usb_reset_device()
to try to rebind an interface that has been deallocated (see
http://marc.info/?l=linux-usb&m=142175717016628&w=2 for details).
Acquiring the extra references prevents this failure.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Russell King - ARM Linux <linux@arm.linux.org.uk>
Reported-by: Olivier Sobrie <olivier@sobrie.be>
Tested-by: Olivier Sobrie <olivier@sobrie.be>
Cc: stable <stable@vger.kernel.org> # 3.19
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-01-25 20:54:17 +08:00
Linus Torvalds
e7cf773d43 USB patches for 3.19-rc1
Here's the big set of USB and PHY patches for 3.19-rc1.
 
 The normal churn in the USB gadget area is in here, as well as xhci and
 other individual USB driver updates.  The PHY tree is also in here, as
 there were dependancies on the USB tree.
 
 All of these have been in linux-next.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB updates from Greg KH:
 "Here's the big set of USB and PHY patches for 3.19-rc1.

  The normal churn in the USB gadget area is in here, as well as xhci
  and other individual USB driver updates.  The PHY tree is also in
  here, as there were dependancies on the USB tree.

  All of these have been in linux-next"

* tag 'usb-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (351 commits)
  arm: omap3: twl: remove usb phy init data
  usbip: fix error handling in stub_probe()
  usb: gadget: udc: missing curly braces
  USB: mos7720: delete some unneeded code
  wusb: replace memset by memzero_explicit
  usbip: remove unneeded structure
  usb: xhci: fix comment for PORT_DEV_REMOVE
  xhci: don't use the same variable for stopped and halted rings current TD
  xhci: clear extra bits from slot context when setting max exit latency
  xhci: cleanup finish_td function
  USB: adutux: NULL dereferences on disconnect
  usb: chipidea: fix platform_no_drv_owner.cocci warnings
  usb: chipidea: Fixed a few typos in comments
  Documentation: bindings: add doc for the USB2 ChipIdea USB driver
  usb: chipidea: add a usb2 driver for ci13xxx
  usb: chipidea: fix phy handling
  usb: chipidea: remove duplicate dev_set_drvdata for host_start
  usb: chipidea: parameter 'mode' isn't needed for hw_device_reset
  usb: chipidea: add controller reset API
  usb: chipidea: remove flag CI_HDRC_REQUIRE_TRANSCEIVER
  ...
2014-12-14 14:57:16 -08:00
Rafael J. Wysocki
ceb6c9c862 USB / PM: Drop CONFIG_PM_RUNTIME from the USB core
After commit b2b49ccbdd (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so quite a few
depend on CONFIG_PM (or even dropped in some cases).

Replace CONFIG_PM_RUNTIME with CONFIG_PM in the USB core code
and documentation.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-12-04 00:51:54 +01:00
Greg Kroah-Hartman
69b7290e51 Merge 3.18-rc4 into usb-next.
This resolves a conflict in drivers/usb/host/Kconfig

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-10 12:10:24 +09:00
Peter Chen
b2108f1e51 usb: core: notify disconnection when core detects disconnect
It is safe to call notify disconnect when the usb core
thinks the device is disconnected.

This commit also fixes one bug found at below situation:
we have not enabled usb wakeup, we do system suspend when
there is an usb device at the port, after suspend, we plug out
the usb device, then plug in device again. At that time,
the nofity disconnect was not called at current code, as
the controller doesn't know the usb device was disconnected
during the suspend, but USB core knows the port has changed
during that periods.

So to fix this problem, and let the usb core call notify disconnect.

Cc: 3.17+ <stable@vger.kernel.org>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-03 19:29:55 -08:00
Tony Zheng
01ed67dc70 usb: core: need to call usb_phy_notify_connect after device setup
Since we notify disconnecting based on the usb device is existed
(port_dev->child, the child device at roothub is not NULL), we
need to notify connect after device has been registered.

This fixes a bug that do fast plug in/out test, and the notify_disconnect
is not called due to roothub child is NULL and the enumeration has failed.

Cc: v3.17+ <stable@vger.kernel.org>
Signed-off-by: Tony Zheng <Tony.Zheng@freescale.com>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-03 15:48:45 -08:00
Sudip Mukherjee
527307eacb usb: hub: remove unused variable
the integer variable 'feature' was not being used anywhere in the function.
so it is safe to remove the variable.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-03 15:38:17 -08:00
Josef Gajdusek
e50a322e51 usb: Do not re-read descriptors for wired devices in usb_authorize_device()
This patch modifies the usb_authorize_device() function such as that it does
not reload the device descriptor for wired devices. The reasons for this
are as follows:

* Some devices dislike the master requesting the descriptor from them twice,
  failing on the usb_get_device_descriptor() call with -ETIMEOUT. Observed this
  on my Pretec 16GB flash drive (4146:ba65).

* Malicious device could send two different descriptors - one before
  authorization, used by userspace to determine whether to authorize it and
  second to be actually used by the kernel when determining which drivers to
  bind.

Signed-off-by: Josef Gajdusek <atx@atx.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-03 15:34:00 -08:00
Antoine Tenart
3d46e73dfd usb: rename phy to usb_phy in HCD
The USB PHY member of the HCD structure is renamed to 'usb_phy' and
modifications are done in all drivers accessing it.
This is in preparation to adding the generic PHY support.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
[Sergei: added missing 'drivers/usb/misc/lvstest.c' file, resolved rejects,
updated changelog.]
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-29 11:52:59 -04:00
Peter Chen
e5a9d62199 usb: core: return -ENOTSUPP for all targeted hosts
The current code only returns -ENOTSUPP for OTG host, but in fact,
embedded host also needs to returns -ENOTSUPP if the peripheral
is not at TPL.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-29 11:50:39 -04:00
Petr Mladek
638139eb95 usb: hub: allow to process more usb hub events in parallel
It seems that only choose_devnum() was not ready to process more hub
events at the same time.

All should be fine if we take bus->usb_address0_mutex there. It will
make sure that more devnums will not be chosen for the given bus and
the related devices at the same time.

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 22:33:19 -07:00
Petr Mladek
37ebb54915 usb: hub: rename khubd to hub_wq in documentation and comments
USB hub has started to use a workqueue instead of kthread. Let's update
the documentation and comments here and there.

This patch mostly just replaces "khubd" with "hub_wq". There are only few
exceptions where the whole sentence was updated. These more complicated
changes can be found in the following files:

	   Documentation/usb/hotplug.txt
	   drivers/net/usb/usbnet.c
	   drivers/usb/core/hcd.c
	   drivers/usb/host/ohci-hcd.c
	   drivers/usb/host/xhci.c

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 22:33:19 -07:00
Petr Mladek
59d48b3f1f usb: hub: rename usb_kick_khubd() to usb_kick_hub_wq()
USB hub started to use a workqueue instead of kthread. Let's make it clear from
the function names.

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 22:33:19 -07:00
Petr Mladek
32a6958998 usb: hub: convert khubd into workqueue
There is no need to have separate kthread for handling USB hub events.
It is more elegant to use the workqueue framework.

The workqueue is allocated as freezable because the original thread was
freezable as well.

Also it is allocated as ordered because the code is not ready for parallel
processing of hub events, see choose_devnum().

struct usb_hub is passed via the work item. Therefore we do not need
hub_event_list.

Also hub_thread() is not longer needed. It would call only hub_event().
The rest of the code did manipulate the kthread and it is handled by the
workqueue framework now.

kick_khubd is renamed to kick_hub_wq() to make the function clear. And the
protection against races is done another way, see below.

hub_event_lock has been removed. It cannot longer be used to protect struct
usb_hub between hub_event() and hub_disconnect(). Instead we need to get
hub->kref already in kick_hub_wq().

The lock is not really needed for the other scenarios as well. queue_work()
returns whether it succeeded. We could revert the needed operations
accordingly. This is enough to avoid duplicity and inconsistencies.

Yes, the removed lock causes that there is not longer such a strong
synchronization between scheduling the work and manipulating
hub->disconnected.

But kick_hub_wq() must never be called together with hub_disconnect()
otherwise even the original code would have failed. Any callers are
responsible for this.

Therefore the only problem is that hub_disconnect() could be called in parallel
with hub_event(). But this was possible even in the past. struct usb_hub is
still guarded by hub->kref and released in hub_events() when needed.

Note that the source file is still full of the obsolete "khubd" strings.
Let's remove them in a follow up patch. This patch already is complex enough.

Thanks a lot Alan Stern <stern@rowland.harvard.edu> for code review, many useful
tips and guidance. Also thanks to Tejun Heo <tj@kernel.org> for hints how to
allocate the workqueue.

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 22:33:19 -07:00
Petr Mladek
eb6e292487 usb: hub: rename hub_events() to hub_event() and handle only one event there
We would like to convert khubd kthread to a workqueue. As a result hub_events()
will handle only one event per call.

In fact, we could do this already now because there is another cycle in
hub_thread(). It calls hub_events() until hub_event_list is empty.

This patch renames the function to hub_event(), removes the while cycle, and
renames the goto targets from loop* to out*.

When touching the code, it fixes also formatting of dev_err() and dev_dbg()
calls to make checkpatch.pl happy :-)

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 22:31:12 -07:00
Petr Mladek
5d14f32383 usb: hub: keep hub->dev reference all the time when struct usb_hub lives
This is just a small optimization of the fix from the commit c605f3cdff
("usb: hub: take hub->hdev reference when processing from eventlist).

We do not need to take the reference for each event. Instead we could get it
when struct usb_hub is allocated and put it when it is released. By other words,
we could handle it the same way as the reference for hub->intfdev.

The motivation is that it will make the life easier when switching from khubd
kthread to a workqueue.

Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 22:31:11 -07:00
Lu Baolu
ddbe1fca0b USB: Add device quirk for ASUS T100 Base Station keyboard
This full-speed USB device generates spurious remote wakeup event
as soon as USB_DEVICE_REMOTE_WAKEUP feature is set. As the result,
Linux can't enter system suspend and S0ix power saving modes once
this keyboard is used.

This patch tries to introduce USB_QUIRK_IGNORE_REMOTE_WAKEUP quirk.
With this quirk set, wakeup capability will be ignored during
device configure.

This patch could be back-ported to kernels as old as 2.6.39.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 22:20:59 -07:00
Peter Chen
026f3fcbb0 usb: core: TPL should apply for both OTG and EH
According to On-The-Go and Embedded Host Supplement to the USB Revision
2.0 Specification, the targeted hosts (non-PC hosts) include both
embedded hosts and otg, and each targeted host product defines the
set of supported peripherals on a TPL (Targeted Peripheral List). So,
TPL should apply for both OTG and embedded host, and the otg support is
not a must for embedded host.

The TPL support feature will only be effect when CONFIG_USB_OTG_WHITELIST
has been chosen and hcd->tpl_support flag is set, it can avoid the enumeration
fails problem for the user who chooses CONFIG_USB_OTG_WHITELIST wrongly.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:28:41 -07:00
Johan Hovold
2a159389bf USB: core: add device-qualifier quirk
Add new quirk for devices that cannot handle requests for the
device_qualifier descriptor.

A USB-2.0 compliant device must respond to requests for the
device_qualifier descriptor (even if it's with a request error), but at
least one device is known to misbehave after such a request.

Suggested-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:15:39 -07:00
Joe Lawrence
c605f3cdff usb: hub: take hub->hdev reference when processing from eventlist
During surprise device hotplug removal tests, it was observed that
hub_events may try to call usb_lock_device on a device that has already
been freed. Protect the usb_device by taking out a reference (under the
hub_event_lock) when hub_events pulls it off the list, returning the
reference after hub_events is finished using it.

Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Suggested-by: David Bulkow <david.bulkow@stratus.com> for using kref
Suggested-by: Alan Stern <stern@rowland.harvard.edu> for placement
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-10 13:32:35 -07:00
Greg Kroah-Hartman
a9ef803d74 USB: fix build error with CONFIG_PM_RUNTIME disabled
commit bdd405d2a5 ("usb: hub: Prevent hub autosuspend if
usbcore.autosuspend is -1") causes a build error if CONFIG_PM_RUNTIME is
disabled.  Fix that by doing a simple #ifdef guard around it.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Roger Quadros <rogerq@ti.com>
Cc: Michael Welling <mwelling@emacinc.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-08-27 16:55:29 -07:00
Roger Quadros
bdd405d2a5 usb: hub: Prevent hub autosuspend if usbcore.autosuspend is -1
If user specifies that USB autosuspend must be disabled by module
parameter "usbcore.autosuspend=-1" then we must prevent
autosuspend of USB hub devices as well.

commit 596d789a21 introduced in v3.8 changed the original behaivour
and stopped respecting the usbcore.autosuspend parameter for hubs.

Fixes: 596d789a21 "USB: set hub's default autosuspend delay as 0"

Cc: [3.8+] <stable@vger.kernel.org>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Tested-by: Michael Welling <mwelling@emacinc.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-08-26 15:59:14 -07:00
Peter Chen
5b1dc209d6 usb: core: fix below build warning
linux-2.6/drivers/usb/core/hub.c: In function 'usb_disconnect':
linux-2.6/drivers/usb/core/hub.c:2110: warning: 'hub' may be used uninitialized in this function
linux-2.6/drivers/usb/core/hub.c:2111: warning: 'port1' may be used uninitialized in this function

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-08-19 11:28:53 -05:00
Takashi Iwai
dd5f5006d1 usbcore: Fix wrong device in an error message in hub_port_connect()
The commit [5ee0f803cc: usbcore: don't log on consecutive debounce
failures of the same port] added the check of the reliable port, but
it also replaced the device argument to dev_err() wrongly, which leads
to a NULL dereference.

This patch restores the right device, port_dev->dev.  Also, since
dev_err() itself shows the port number, reduce the port number shown
in the error message, essentially reverting to the state before the
commit 5ee0f803cc.

[The fix suggested by Hannes, and the error message cleanup suggested
 by Alan Stern]

Fixes: 5ee0f803cc ('usbcore: don't log on consecutive debounce failures of the same port')
Reported-by: Hannes Reinecke <hare@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-08-19 11:16:08 -05:00
Linus Torvalds
ae9b475ebe USB patches for 3.17-rc1
Here is the big USB driver update for 3.17-rc1.
 
 Loads of gadget driver changes in here, including some big file
 movements to make things easier to manage over time.  There's also the
 usual xhci and uas driver updates, and a handful of other changes in
 here.  The changelog has the full details.
 
 All of these have been in linux-next for a while.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-3.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB updates from Greg KH:
 "Here is the big USB driver update for 3.17-rc1.

  Loads of gadget driver changes in here, including some big file
  movements to make things easier to manage over time.  There's also the
  usual xhci and uas driver updates, and a handful of other changes in
  here.  The changelog has the full details.

  All of these have been in linux-next for a while"

* tag 'usb-3.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (211 commits)
  USB: devio: fix issue with log flooding
  uas: Log a warning when we cannot use uas because the hcd lacks streams
  uas: Only complain about missing sg if all other checks succeed
  xhci: Add missing checks for xhci_alloc_command failure
  xhci: Rename Asrock P67 pci product-id to EJ168
  xhci: Blacklist using streams on the Etron EJ168 controller
  uas: Limit qdepth to 32 when connected over usb-2
  uwb/whci: use correct structure type name in sizeof
  usb-core bInterval quirk
  USB: serial: ftdi_sio: Add support for new Xsens devices
  USB: serial: ftdi_sio: Annotate the current Xsens PID assignments
  usb: chipidea: debug: fix sparse non static symbol warnings
  usb: ci_hdrc_imx doc: fsl,usbphy is required
  usb: ci_hdrc_imx: Return -EINVAL for missing USB PHY
  usb: core: allow zero packet flag for interrupt urbs
  usb: lvstest: Fix sparse warnings generated by kbuild test bot
  USB: core: hcd-pci: free IRQ before disabling PCI device when shutting down
  phy: miphy365x: Represent each PHY channel as a DT subnode
  phy: miphy365x: Provide support for the MiPHY356x Generic PHY
  phy: miphy365x: Add Device Tree bindings for the MiPHY365x
  ...
2014-08-04 20:11:28 -07:00
Pratyush Anand
a40178b2fa USB: Fix persist resume of some SS USB devices
Problem Summary: Problem has been observed generally with PM states
where VBUS goes off during suspend. There are some SS USB devices which
take longer time for link training compared to many others.  Such
devices fail to reconnect with same old address which was associated
with it before suspend.

When system resumes, at some point of time (dpm_run_callback->
usb_dev_resume->usb_resume->usb_resume_both->usb_resume_device->
usb_port_resume) SW reads hub status. If device is present,
then it finishes port resume and re-enumerates device with same
address. If device is not present then, SW thinks that device was
removed during suspend and therefore does logical disconnection
and removes all the resource allocated for this device.

Now, if I put sufficient delay just before root hub status read in
usb_resume_device then, SW sees always that device is present. In normal
course(without any delay) SW sees that no device is present and then SW
removes all resource associated with the device at this port.  In the
latter case, after sometime, device says that hey I am here, now host
enumerates it, but with new address.

Problem had been reproduced when I connect verbatim USB3.0 hard disc
with my STiH407 XHCI host running with 3.10 kernel.

I see that similar problem has been reported here.
https://bugzilla.kernel.org/show_bug.cgi?id=53211
Reading above it seems that bug was not in 3.6.6 and was present in 3.8
and again it was not present for some in 3.12.6, while it was present
for few others. I tested with 3.13-FC19 running at i686 desktop, problem
was still there. However, I was failed to reproduce it with 3.16-RC4
running at same i686 machine. I would say it is just a random
observation. Problem for few devices is always there, as I am unable to
find a proper fix for the issue.

So, now question is what should be the amount of delay so that host is
always able to recognize suspended device after resume.

XHCI specs 4.19.4 says that when Link training is successful, port sets
CSC bit to 1. So if SW reads port status before successful link
training, then it will not find device to be present.  USB Analyzer log
with such buggy devices show that in some cases device switch on the
RX termination after long delay of host enabling the VBUS. In few other
cases it has been seen that device fails to negotiate link training in
first attempt. It has been reported till now that few devices take as
long as 2000 ms to train the link after host enabling its VBUS and
RX termination. This patch implements a 2000 ms timeout for CSC bit to set
ie for link training. If in a case link trains before timeout, loop will
exit earlier.

This patch implements above delay, but only for SS device and when
persist is enabled.

So, for the good device overhead is almost none. While for the bad
devices penalty could be the time which it take for link training.
But, If a device was connected before suspend, and was removed
while system was asleep, then the penalty would be the timeout ie
2000 ms.

Results:

Verbatim USB SS hard disk connected with STiH407 USB host running 3.10
Kernel resumes in 461 msecs without this patch, but hard disk is
assigned a new device address. Same system resumes in 790 msecs with
this patch, but with old device address.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pratyush Anand <pratyush.anand@st.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-18 16:18:11 -07:00
Oliver Neukum
5ee0f803cc usbcore: don't log on consecutive debounce failures of the same port
Some laptops have an internal port for a BT device which picks
up noise when the kill switch is used, but not enough to trigger
printk_rlimit(). So we shouldn't log consecutive faults of this kind.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-18 16:18:10 -07:00
Gavin Guo
bb86cf569b usb: Check if port status is equal to RxDetect
When using USB 3.0 pen drive with the [AMD] FCH USB XHCI Controller
[1022:7814], the second hotplugging will experience the USB 3.0 pen
drive is recognized as high-speed device. After bisecting the kernel,
I found the commit number 41e7e056cd
(USB: Allow USB 3.0 ports to be disabled.) causes the bug. After doing
some experiments, the bug can be fixed by avoiding executing the function
hub_usb3_port_disable(). Because the port status with [AMD] FCH USB
XHCI Controlleris [1022:7814] is already in RxDetect
(I tried printing out the port status before setting to Disabled state),
it's reasonable to check the port status before really executing
hub_usb3_port_disable().

Fixes: 41e7e056cd (USB: Allow USB 3.0 ports to be disabled.)
Signed-off-by: Gavin Guo <gavin.guo@canonical.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-17 17:14:01 -07:00
Dan Williams
3cd12f9151 usb: force warm reset to break link re-connect livelock
Resuming a powered down port sometimes results in the port state being
stuck in the training sequence.

 hub 3-0:1.0: debounce: port 1: total 2000ms stable 0ms status 0x2e0
 port1: can't get reconnection after setting port  power on, status -110
 hub 3-0:1.0: port 1 status 0000.02e0 after resume, -19
 usb 3-1: can't resume, status -19
 hub 3-0:1.0: logical disconnect on port 1

In the case above we wait for the port re-connect timeout of 2 seconds
and observe that the port status is USB_SS_PORT_LS_POLLING (although it
is likely toggling between this state and USB_SS_PORT_LS_RX_DETECT).
This is indicative of a case where the device is failing to progress the
link training state machine.

It is resolved by issuing a warm reset to get the hub and device link
state machines back in sync.

 hub 3-0:1.0: debounce: port 1: total 2000ms stable 0ms status 0x2e0
 usb usb3: port1 usb_port_runtime_resume requires warm reset
 hub 3-0:1.0: port 1 not warm reset yet, waiting 50ms
 usb 3-1: reset SuperSpeed USB device number 2 using xhci_hcd

After a reconnect timeout when we expect the device to be present, force
a warm reset of the device.  Note that we can not simply look at the
link status to determine if a warm reset is required as any of the
training states USB_SS_PORT_LS_POLLING, USB_SS_PORT_LS_RX_DETECT, or
USB_SS_PORT_LS_COMP_MOD are valid states that do not indicate the need
for warm reset by themselves.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Vincent Palatin <vpalatin@chromium.org>
Cc: Lan Tianyu <tianyu.lan@intel.com>
Cc: Ksenia Ragiadakou <burzalodowa@gmail.com>
Cc: Vivek Gautam <gautam.vivek@samsung.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Sunil Joshi <joshi@samsung.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Acked-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-09 15:43:12 -07:00
Pratyush Anand
51df62ff74 usb: allow lpm (en/dis)able only if device is atleast in default state
When a USB device is disconnected, usb_unbind_interface is called, which
tries to enable and disable LPM. usb_enable_lpm also try to send a
control command SET SEL to the device.
Since device is already disconnected, therefore it does not make sense
to execute usb_(en/dis)able_lpm.
This patch returns from usb_(en/dis)able_lpm, if device was not in
default state atleast.

Signed-off-by: Pratyush Anand <pratyush.anand@st.com>
Tested-by: Aymen Bouattay <aymen.bouattay@st.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-09 15:41:34 -07:00
Dan Williams
e3d1050555 usb: fix hub-port pm_runtime_enable() vs runtime pm transitions
Commit 9262c19d14 "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: 9262c19d14 ("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>
2014-06-17 17:04:39 -07:00
Dan Williams
b658b8f5c0 usb: improve "not suspended yet" message in hub_suspend()
Reading through a recent bug report [1], Alan notes:

  "Dan, the warning message in hub_suspend() should mention that the
   child device isn't suspended yet."

...update the warning from:

  "usb usb3-port4: not suspended yet"

...to:

   "usb usb3-port4: device 3-4: not suspended yet"

[1]: http://marc.info/?l=linux-usb&m=140290586301336&w=2

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>
2014-06-17 16:44:57 -07:00
Dan Williams
e3d9558082 usb: fix ->update_hub_device() vs hdev->maxchild
Commit d8521afe35 "usb: assign default peer ports for root hubs"
delayed marking a hub valid (set hdev->maxchild) until it had been fully
configured and to enable the publishing of valid hubs to be serialized
by usb_port_peer_mutex.

However, xhci_update_hub_device() in some cases depends on
hdev->maxchild already being set.  Do the minimal fix and move it after
the setting of hdev->maxchild.

Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Tested-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-06-17 16:44:57 -07:00
Linus Torvalds
3f17ea6dea Merge branch 'next' (accumulated 3.16 merge window patches) into master
Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.

* accumulated work in next: (6809 commits)
  ufs: sb mutex merge + mutex_destroy
  powerpc: update comments for generic idle conversion
  cris: update comments for generic idle conversion
  idle: remove cpu_idle() forward declarations
  nbd: zero from and len fields in NBD_CMD_DISCONNECT.
  mm: convert some level-less printks to pr_*
  MAINTAINERS: adi-buildroot-devel is moderated
  MAINTAINERS: add linux-api for review of API/ABI changes
  mm/kmemleak-test.c: use pr_fmt for logging
  fs/dlm/debug_fs.c: replace seq_printf by seq_puts
  fs/dlm/lockspace.c: convert simple_str to kstr
  fs/dlm/config.c: convert simple_str to kstr
  mm: mark remap_file_pages() syscall as deprecated
  mm: memcontrol: remove unnecessary memcg argument from soft limit functions
  mm: memcontrol: clean up memcg zoneinfo lookup
  mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
  mm/mempool.c: update the kmemleak stack trace for mempool allocations
  lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
  mm: introduce kmemleak_update_trace()
  mm/kmemleak.c: use %u to print ->checksum
  ...
2014-06-08 11:31:16 -07:00
Stephen Rothwell
4a95b1fce9 usb: hub_handle_remote_wakeup() only exists for CONFIG_PM=y
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-06-02 15:16:33 -07:00
Dan Williams
7027df36e4 usb: resume child device when port is powered on
Unconditionally wake up the child device when the power session is
recovered.

This addresses the following scenarios:

1/ The device may need a reset on power-session loss, without this
   change port power-on recovery exposes khubd to scenarios that
   usb_port_resume() is set to handle.  Prior to port power control the
   only time a power session would be lost is during dpm_suspend of the
   hub.  In that scenario usb_port_resume() is guaranteed to be called
   prior to khubd running for that port.  With this change we wakeup the
   child device as soon as possible (prior to khubd running again for this
   port).

   Although khubd has facilities to wake a child device it will only do
   so if the portstatus / portchange indicates a suspend state.  In the
   case of port power control we are not coming from a hub-port-suspend
   state.  This implementation simply uses pm_request_resume() to wake the
   device and relies on the port_dev->status_lock to prevent any collisions
   between khubd and usb_port_resume().

2/ This mechanism rate limits port power toggling.  The minimum port
   power on/off period is now gated by the child device suspend/resume
   latency.  Empirically this mitigates devices downgrading their connection
   on perceived instability of the host connection.  This ratelimiting is
   really only relevant to port power control testing, but it is a nice
   side effect of closing the above race.  Namely, the race of khubd for
   the given port running while a usb_port_resume() event is pending.

3/ Going forward we are finding that power-session recovery requires
   warm-resets (http://marc.info/?t=138659232900003&r=1&w=2).  This
   mechanism allows for warm-resets to be requested at the same point in
   the resume path for hub dpm_suspend power session losses, or port
   rpm_suspend power session losses.

4/ If the device *was* disconnected the only time we'll know for sure is
   after a failed resume, so it's necessary for usb_port_runtime_resume()
   to expedite a usb_port_resume() to clean up the removed device.  The
   reasoning for this is "least surprise" for the user. Turning on a port
   means that hotplug detection is again enabled for the port, it is
   surprising that devices that were removed while the port was off are not
   disconnected until they are attempted to be used.  As a user "why would
   I try to use a device I removed from the system?"

1, 2, and 4 are not a problem in the system dpm_resume() case because,
although the power-session is lost, khubd is frozen until after device
resume.  For the rpm_resume() case pm_request_resume() is used to
request re-validation of the device, and if it happens to collide with a
khubd run we rely on the port_dev->status_lock to synchronize those
operations.

Besides testing, the primary scenario where this mechanism is expected
to be triggered is when the user changes the port power policy
(control/pm_qos_no_poweroff, or power/control).   Each time power is
enabled want to revalidate the child device, where the revalidation is
handled by usb_port_resume().

Given that this arranges for port_dev->child to be de-referenced in
usb_port_runtime_resume() we need to make sure not to collide with
usb_disconnect() that frees the usb_device.  To this end we hold the
port active with the "child_usage" reference across the disconnect
event.  Subsequently, the need to access hub->child_usage_bits lead to
the creation of hub_disconnect_children() to remove any ambiguity of
which "hub" is being acted on in usb_disconnect() (prompted-by sharp
eyes from Alan).

Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Acked-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>
2014-05-27 17:25:37 -07:00