How it's supposed to work:
--------------------------
USB 2.0 Link PM is a lower power state that some newer USB 2.0 devices
support. USB 3.0 devices certified by the USB-IF are required to
support it if they are plugged into a USB 2.0 only port, or a USB 2.0
cable is used. USB 2.0 Link PM requires both a USB device and a host
controller that supports USB 2.0 hardware-enabled LPM.
USB 2.0 Link PM is designed to be enabled once by software, and the host
hardware handles transitions to the L1 state automatically. The premise
of USB 2.0 Link PM is to be able to put the device into a lower power
link state when the bus is idle or the device NAKs USB IN transfers for
a specified amount of time.
...but hardware is broken:
--------------------------
It turns out many USB 3.0 devices claim to support USB 2.0 Link PM (by
setting the LPM bit in their USB 2.0 BOS descriptor), but they don't
actually implement it correctly. This manifests as the USB device
refusing to respond to transfers when it is plugged into a USB 2.0 only
port under the Haswell-ULT/Lynx Point LP xHCI host.
These devices pass the xHCI driver's simple test to enable USB 2.0 Link
PM, wait for the port to enter L1, and then bring it back into L0. They
only start to break when L1 entry is interleaved with transfers.
Some devices then fail to respond to the next control transfer (usually
a Set Configuration). This results in devices never enumerating.
Other mass storage devices (such as a later model Western Digital My
Passport USB 3.0 hard drive) respond fine to going into L1 between
control transfers. They ACK the entry, come out of L1 when the host
needs to send a control transfer, and respond properly to those control
transfers. However, when the first READ10 SCSI command is sent, the
device NAKs the data phase while it's reading from the spinning disk.
Eventually, the host requests to put the link into L1, and the device
ACKs that request. Then it never responds to the data phase of the
READ10 command. This results in not being able to read from the drive.
Some mass storage devices (like the Corsair Survivor USB 3.0 flash
drive) are well behaved. They ACK the entry into L1 during control
transfers, and when SCSI commands start coming in, they NAK the requests
to go into L1, because they need to be at full power.
Not all USB 3.0 devices advertise USB 2.0 link PM support. My Point
Grey USB 3.0 webcam advertises itself as a USB 2.1 device, but doesn't
have a USB 2.0 BOS descriptor, so we don't enable USB 2.0 Link PM. I
suspect that means the device isn't certified.
What do we do about it?
-----------------------
There's really no good way for the kernel to test these devices.
Therefore, the kernel needs to disable USB 2.0 Link PM by default, and
distros will have to enable it by writing 1 to the sysfs file
/sys/bus/usb/devices/../power/usb2_hardware_lpm. Rip out the xHCI Link
PM test, since it's not sufficient to detect these buggy devices, and
don't automatically enable LPM after the device is addressed.
This patch should be backported to kernels as old as 3.11, that
contain the commit a558ccdcc7 "usb: xhci:
add USB2 Link power management BESL support". Without this fix, some
USB 3.0 devices will not enumerate or work properly under USB 2.0 ports
on Haswell-ULT systems.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
This patch straightens out some locking issues in the USB sysfs
interface:
Deauthorization will destroy existing configurations.
Attributes that read from udev->actconfig need to lock the
device to prevent races. Likewise for the rawdescriptor
values.
Attributes that access an interface's current alternate
setting should use ACCESS_ONCE() to obtain the cur_altsetting
pointer, to protect against concurrent altsetting changes.
The supports_autosuspend() attribute routine accesses values
from an interface's driver, so it should lock the interface
(rather than the usb_device) to protect against concurrent
unbinds. Once this is done, the routine can be simplified
considerably.
Scalar values that are stored directly in the usb_device structure are
always available. They do not require any locking. The same is true
of the cached interface string descriptor, because it is not
deallocated until the usb_host_interface structure is destroyed.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of having to audit all sysfs attributes, to ensure we get them
right, use the default macros the driver core provides us (read-only,
read-write) to make the code simpler, and to prevent any mistakes from
ever happening.
Signed-off-by: Greg 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: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
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: Alan Stern <stern@rowland.harvard.edu>
CC: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The USB 2.0 specification says that bMaxPower is the maximum power
consumption expressed in 2 mA units and the USB 3.0 specification says
that it is expressed in 8 mA units.
This patch adds a helper function usb_get_max_power() which computes the
value based on config & usb_device's speed value. The the device descriptor
dump computes the value on its own.
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since the attribute avoid_reset_quirk is work for all devices including
those devices that can't morph, convert USB_QUIRK_RESET_MORPHS to
USB_QUIRK_RESET.
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In USB, the word "config" already has aseparate meaning. So it will
cause confusion if use "config" as variable's name for other purposes.
This patch is to convert the "config" to "val"
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
USB 3.0 devices can optionally support Latency Tolerance Messaging
(LTM). Add a new sysfs file in the device directory to show whether a
device is LTM capable. This file will be present for both USB 2.0 and
USB 3.0 devices.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Some composite USB devices provide multiple interfaces
with different functions, all using "vendor-specific"
for class/subclass/protocol. Another OS use interface
numbers to match the driver and interface. It seems
these devices are designed with that in mind - using
static interface numbers for the different functions.
This adds support for matching against the
bInterfaceNumber, allowing such devices to be supported
without having to resort to testing against interface
number whitelists and/or blacklists in the probe.
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch (as1554) fixes a lockdep false-positive report. The
problem arises because lockdep is unable to deal with the
tree-structured locks created by the device core and sysfs.
This particular problem involves a sysfs attribute method that
unregisters itself, not from the device it was called for, but from a
descendant device. Lockdep doesn't understand the distinction and
reports a possible deadlock, even though the operation is safe.
This is the sort of thing that would normally be handled by using a
nested lock annotation; unfortunately it's not feasible to do that
here. There's no sensible way to tell sysfs when attribute removal
occurs in the context of a parent attribute method.
As a workaround, the patch adds a new flag to struct attribute
telling sysfs not to inform lockdep when it acquires a readlock on a
sysfs_dirent instance for the attribute. The readlock is still
acquired, but lockdep doesn't know about it and hence does not
complain about impossible deadlock scenarios.
Also added are macros for static initialization of attribute
structures with the ignore_lockdep flag set. The three offending
attributes in the USB subsystem are converted to use the new macros.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Tejun Heo <tj@kernel.org>
CC: Eric W. Biederman <ebiederm@xmission.com>
CC: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Userspace may want to make policy decisions based on whether or not a
given USB device is removable. Add a per-device member and support
for exposing it in sysfs. Information sources to populate it will be
added later.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch adds sysfs support to xHCI usb2 hardware LPM, so developer can
enable and disable usb2 hardware LPM manually for test purpose.
Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The usb_create_sysfs_intf_files() function always returned zero even
if it failed to create sysfs fails. Since this is a desired behaviour
there is no need to return return code at all. This commit changes
function's return type (form int) to void.
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1428) converts USB over to the new runtime-PM core
autosuspend framework. One slightly awkward aspect of the conversion
is that USB devices will now have two suspend-delay attributes: the
old power/autosuspend file and the new power/autosuspend_delay_ms
file. One expresses the delay time in seconds and the other in
milliseconds, but otherwise they do the same thing. The old attribute
can be deprecated and then removed eventually.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1426) makes use of the new sysfs_merge_group() and
sysfs_unmerge_group() routines to simplify the handling of power
attributes for USB devices.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This allows bin_attr->read,write,mmap callbacks to check file specific data
(such as inode owner) as part of any privilege validation.
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1367) deprecates USB's power/level sysfs attribute in
favor of the power/control attribute provided by the runtime PM core.
The two attributes do the same thing.
It would be nice to replace power/level with a symlink to
power/control, but at the moment sysfs doesn't offer any way to do so.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1366) replaces the private routines
usb_enable_autosuspend() and usb_disable_autosuspend() with calls to
the standard pm_runtime_allow() and pm_runtime_forbid() functions in
the runtime PM framework. They do the same thing.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1327) changes the way negative autosuspend delays
prevent device from autosuspending. The current code checks for
negative values explicitly in the autosuspend_check() routine. The
updated code keeps things from getting that far by using
usb_autoresume_device() to increment the usage counter when a negative
delay is set, and by using usb_autosuspend_device() to decrement the
usage counter when a non-negative delay is set.
This complicates the set_autosuspend() attribute method code slightly,
but it will reduce the overall power management overhead.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1326) adds usb_enable_autosuspend() and
usb_disable_autosuspend() routines for use by drivers. If a driver
knows that its device can handle suspends and resumes correctly, it
can enable autosuspend all by itself. This is equivalent to the user
writing "auto" to the device's power/level attribute.
The implementation differs slightly from what it used to be. Now
autosuspend is disabled simply by doing usb_autoresume_device() (to
increment the usage counter) and enabled by doing
usb_autosuspend_device() (to decrement the usage counter).
The set_level() attribute method is updated to use the new routines,
and the USB Power-Management documentation is updated.
The patch adds a usb_enable_autosuspend() call to the hub driver's
probe routine, allowing the special-case code for hubs in quirks.c to
be removed.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1325) changes the locking for the persist_enabled flag
in struct usb_device. Now it is protected by the device lock, along
with all its neighboring bit flags, instead of the PM lock (which is
about to vanish anyway).
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Rahul Bedarkar
Sarah Sharp
Matthias Beyer
Alan Stern
Greg Kroah-Hartman
Mathias Nyman
Sebastian Andrzej Siewior
Lan Tianyu
Bjørn Mork
Matthew Garrett
Al Viro
Andiry Xu
Michal Nazarewicz
Chris Wright