Commit Graph

93 Commits

Author SHA1 Message Date
Alan Stern
9bbdf1e0af USB: convert to the runtime PM framework
This patch (as1329) converts the USB stack over to the PM core's
runtime PM framework.  This involves numerous changes throughout
usbcore, especially to hub.c and driver.c.  Perhaps the most notable
change is that CONFIG_USB_SUSPEND now depends on CONFIG_PM_RUNTIME
instead of CONFIG_PM.

Several fields in the usb_device and usb_interface structures are no
longer needed.  Some code which used to depend on CONFIG_USB_PM now
depends on CONFIG_USB_SUSPEND (requiring some rearrangement of header
files).

The only visible change in behavior should be that following a system
sleep (resume from RAM or resume from hibernation), autosuspended USB
devices will be resumed just like everything else.  They won't remain
suspended.  But if they aren't in use then they will naturally
autosuspend again in a few seconds.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-02 14:54:12 -08:00
Alan Stern
088f7fec8a USB: implement usb_enable_autosuspend
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>
2010-03-02 14:54:10 -08:00
Alan Stern
f661c6f8c6 USB: check the endpoint type against the pipe type
This patch (as1316) adds some error checking to usb_submit_urb().
It's conditional on CONFIG_USB_DEBUG, so it won't affect normal users.
The new check makes sure that the actual type of the endpoint
described by urb->pipe agrees with the type encoded in the pipe value.

The USB error code documentation is updated to include the code
returned by the new check, and the usbfs SUBMITURB handler is updated
to use the correct pipe type when legacy user code tries to submit a
bulk transfer to an interrupt endpoint.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-02 14:53:07 -08:00
Alan Stern
baf67741bf USB: power management documentation update
This patch (as1313) updates the documentation concerning USB power
management.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-23 11:34:09 -08:00
Alan Stern
8e4ceb38eb USB: prepare for changover to Runtime PM framework
This patch (as1303) revises the USB Power Management infrastructure to
make it compatible with the new driver-model Runtime PM framework:

	Drivers are no longer allowed to access intf->pm_usage_cnt
	directly; the PM framework manages its own usage counters.

	usb_autopm_set_interface() is eliminated, because it directly
	sets intf->pm_usage_cnt.

	usb_autopm_enable() and usb_autopm_disable() are eliminated,
	because they call usb_autopm_set_interface().

	usb_autopm_get_interface_no_resume() and
	usb_autopm_put_interface_no_suspend() are added.  They
	correspond to pm_runtime_get_noresume() and
	pm_runtime_put_noidle() in the PM framework.

	The power/level attribute no longer accepts "suspend", only
	"on" and "auto".  The PM framework doesn't allow devices to be
	forced into a suspended mode.

The hub driver contains the only code that violates the new
guidelines.  It is updated to use the new interface routines instead.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11 11:55:25 -08:00
Alan Stern
fb34d53752 USB: remove the auto_pm flag
This patch (as1302) removes the auto_pm flag from struct usb_device.
The flag's only purpose was to distinguish between autosuspends and
external suspends, but that information is now available in the
pm_message_t argument passed to suspend methods.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11 11:55:21 -08:00
Jean Delvare
a87371b477 USB: Fix sysfs paths in documentation
Neither /sys/usb/devices nor /sys/bus/devices exist. The correct path
is /sys/bus/usb/devices.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-09-23 06:46:41 -07:00
Rogério Brito
f0cc82a831 USB: fix paths in usbmon documentation
Hi there.

On Aug 21 2009, Alan Stern wrote:
> On Thu, 20 Aug 2009, Rogério Brito wrote:
> > Again, just reiterating, what I said before, even though I am not sure
> > if I can reproduce it, I will try to.
> 
> A usbmon trace showing what happens when you plug in the drive and 
> when you run smartctl would help.

The documentation for usbmon in the kernel 2.6.31-rc7 kernel doesn't
match what the kernel exposes in the debug fs tree. This patch fixes it.

Signed-off-by: Rogério Brito <rbrito@ime.usp.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-09-23 06:46:37 -07:00
Pete Zaitcev
f4e2332cfc USB: usbmon: touch up the documentation
I think this sentence was confusing regarding the possible size
of the data area.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-09-23 06:46:19 -07:00
Németh Márton
6e22168954 trivial: usb: fix missing space typo in doc
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-06-12 18:01:51 +02:00
Matt LaPlante
19f5946001 trivial: Miscellaneous documentation typo fixes
Fix various typos in documentation txts.

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-06-12 18:01:47 +02:00
Pete Zaitcev
471c604daf USB: usbmon: Add binary API v1
This patch adds an extension to the binary API so it reaches parity with
existing text API (so-called "1u"). The extension delivers additional data,
such as ISO descriptors and the interrupt interval.

Signed-Off-By: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-03-24 16:20:36 -07:00
Randy Dunlap
5872fb94f8 Documentation: move DMA-mapping.txt to Doc/PCI/
Move DMA-mapping.txt to Documentation/PCI/.

DMA-mapping.txt was supposed to be moved from Documentation/ to
Documentation/PCI/.  The 00-INDEX files in those two directories
were updated, along with a few other text files, but the file
itself somehow escaped being moved, so move it and update more
text files and source files with its new location.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
cc:	Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-29 18:19:29 -08:00
Alan Stern
9ac39f28b5 USB: add asynchronous autosuspend/autoresume support
This patch (as1160b) adds support routines for asynchronous autosuspend
and autoresume, with accompanying documentation updates.  There
already are several potential users of this interface, and others are
likely to arise as autosuspend support becomes more widespread.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-01-07 09:59:53 -08:00
David Vrabel
b21a207141 Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into for-upstream
Conflicts:

	drivers/uwb/wlp/eda.c
2009-01-02 13:17:13 +00:00
Phil Endecott
9a9fafb894 USB: fix comment about endianness of descriptors
This patch fixes a comment and clarifies the documentation about the
endianness of descriptors. The current policy is that descriptors will
be little-endian at the API even on big-endian systems; however the
/proc/bus/usb API predates this policy and presents descriptors with
some multibyte fields byte-swapped.

Signed-off-by: Phil Endecott <usb_endian_patch@chezphil.org>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-12-17 10:49:14 -08:00
Peter Korsgaard
c33ba39214 USB: Documentation/usb/gadget_serial.txt: update to match driver use_acm behaviour
Commit 7bb5ea54 (usb gadget serial: use composite gadget framework)
changed the default for the use_acm parameter from 0 to 1.
Update the documentation to match.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-12-17 10:49:13 -08:00
Pete Zaitcev
aacf4a0135 usbmon: drop bogus 0t from usbmon.txt
The example is incorrect: there is no 0t socket (the '1t' format has no
bus number in it). Also, correct the broken sentence for USB Tag.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-12-17 10:49:12 -08:00
David Vrabel
6fae35f9ce uwb: add basic radio manager
The UWB radio manager coordinates the use of the radio between the
PALs that may be using it.  PALs request use of the radio with
uwb_radio_start() and the radio manager will start beaconing if its
not already doing so.  When the last PAL has called uwb_radio_stop()
beaconing will be stopped.

In the future, the radio manager will have a more sophisticated channel
selection algorithm, probably following the Channel Selection Policy
from the WiMedia Alliance when it is finalized.  For now, channel 9
(BG1, TFC1) is selected.

The user may override the channel selected by the radio manager and may
force the radio to stop beaconing.

The WUSB Host Controller PAL makes use of this and there are two new
debug PAL commands that can be used for testing.

Signed-off-by: David Vrabel <david.vrabel@csr.com>
2008-11-19 14:46:33 +00:00
David Vrabel
61e0e79ee3 Merge branch 'master' into for-upstream
Conflicts:

	Documentation/ABI/testing/sysfs-bus-usb
	drivers/Makefile
2008-10-20 16:07:19 +01:00
Geoff Levand
81ab5b8ee6 USB: Fix doc for usb_autopm_enable
Correct errors in the descriptions for usb_autopm_enable
and usb_autopm_disable in the USB PM doc.

Signed-off-by: Geoff Levand <geoff@infradead.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-10-17 14:40:56 -07:00
Oliver Neukum
d1b1944085 USB: Documentation/usb/anchors.txt #2
This adds Documentation for the extensions of the anchor API.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-10-17 14:40:54 -07:00
Harrison Metzger
eb86be5424 USB: Added driver for a Delcom USB 7-segment LED Display
Added basic support for a Delcom USB 7-segment LED Display

Signed-off by: Harrison Metzger <harrisonmetz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-10-17 14:40:51 -07:00
David Vrabel
99ee3a6d45 Merge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/dvrabel/uwb into for-upstream 2008-10-10 11:47:31 +01:00
Oliver Neukum
697e04db56 USB: update of Documentation/usb/anchors.txt
The extended anchor API is documented

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-23 13:58:07 -07:00
Felipe Zimmerle
f1fa035f2b wusb: wusb-cbaf (CBA driver) sysfs ABI simplification
Simplify the sysfs ABI of the wusb-cbaf (Cable Based Association)
driver: use one value per file and cause the write of the CHID to
fetch the CDID (instead of requiring a separate read).

Update the example wusb-cbaf script to work with this revised ABI.

Signed-off-by: Felipe Zimmerle <felipe.zimmerle@indt.org.br>
Signed-off-by: David Vrabel <david.vrabel@csr.com>
2008-09-17 16:54:35 +01:00
Inaky Perez-Gonzalez
99d368bc9e uwb: add initial documentation
Documentation (and example utilities) for the UWB (and WUSB) stacks.

Some of the documentation may be out-of-date.

Signed-off-by: David Vrabel <david.vrabel@csr.com>
2008-09-17 16:54:23 +01:00
Oliver Neukum
f0fa74634c USB: update to Documentation
this mentions a new deadlock due to advanced power management.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-08-13 17:32:52 -07:00
Wolfgang Mües
88d987d6db usb: auerswald: remove driver (obsolete)
This patch removes the auerswald USB driver from the linux kernel
2.6.26.

This driver was included into the kernel mainly to connect to the ISDN
framework. This was done in linux 2.4.x. For 2.6.x, due to the fragile
and moving ISDN support, this connection was never realized, and the
only use of this driver was for device configuration. In the age of DSL,
the demand of ISDN support is getting very low.

Meanwhile, with the advent of libusb, an userspace driver was done for
the device configuration which works fine for linux and mac. (Thanks to
the libusb developers!). The userspace driver is downloadable from the
auerswald web site.

So this driver is obsolete now and has to be removed. Many thanks to all
developers which helped me to bring this driver up and working.

Signed-off-by: Wolfgang Muees <wolfgang@iksw-muees.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-08-13 17:32:47 -07:00
Matt LaPlante
d91958815d Documentation cleanup: trivial misspelling, punctuation, and grammar corrections.
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26 12:00:06 -07:00
Alan Stern
86c57edf60 USB: use reset_resume when normal resume fails
This patch (as1109b) makes USB-Persist more resilient to errors.  With
the current code, if a normal resume fails, it's an unrecoverable
error.  With the patch, if a normal resume fails (and if the device is
enabled for USB-Persist) then a reset-resume is tried.

This fixes the problem reported in Bugzilla #10977.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-21 15:16:48 -07:00
David Brownell
a7707adf9e usb gadget: use new serial core
Teach "gadget serial" to use the new abstracted (and bugfixed) TTY glue,
and remove all the orignal tangled-up code.  Update the documentation
accordingly.  This is a net object code shrink and cleanup; it should
make it a lot easier to see how the TTY glue should accomodate updates
to the TTY layer, be bugfixed, etc.

Notable behavior changes include:  it can now support getty even when
there's no USB connection; it fits properly into the mdev/udev world;
and RX handling is better (throttling works, and low latency).

Configurations with scripts setting up the /dev/ttygserial device node
(with "experimental" major number) may want to change that to be a
symlink pointing to the /dev/ttyGS0 file, as a migration aid; else,
just switch entirely over to mdev/udev.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-21 15:15:59 -07:00
Adrian Bunk
baad4119a3 USB: remove Documentation/usb/uhci.txt
The driver was removed before kernel 2.6.0

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-21 15:15:55 -07:00
Oliver Neukum
08177e12b7 USB: add documentation about callbacks
Add Documentation about callbacks in USB.


Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-04-24 21:16:53 -07:00
Oliver Neukum
e6a79f1f07 USB: add Documentation about usb_anchor
This adds documentation about the new usb anchor infrastructure.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-04-24 21:16:51 -07:00
Matti Linnanvuori
e04d80b03d USB: serial: Remove obsolete contact addresses
Remove obsolete contact addresses.

Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-04-24 21:16:45 -07:00
Alan Stern
eb764c4be1 USB: check serial-number string after device reset
This patch (as1048) extends the descriptor checking after a device is
reset.  Now the SerialNumber string descriptor is compared to its old
value, in addition to the device and configuration descriptors.

As a consequence, the kmalloc() call in usb_string() is now on the
error-handling pathway for usb-storage.  Hence its allocation type is
changed to GFO_NOIO.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-04-24 21:16:33 -07:00
Alan Stern
feccc30d90 USB: remove CONFIG_USB_PERSIST setting
This patch (as1047) removes the USB_PERSIST Kconfig option, enabling
it permanently.  It also prevents the power/persist attribute from
being created for hub devices; there's no point in having it since
USB-PERSIST is always turned on for hubs.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-04-24 21:16:32 -07:00
Robert P. J. Day
15c4a4e2f1 USB:Update mailing list information in documentation
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-03-10 16:42:27 -07:00
Craig W. Nadler
25a010c8c1 USB: add Printer Gadget Driver
G_PRINTER: Adds a USB printer gadget driver for use in printer firmware.

This adds a USB printer gadget driver for use in printer firmware.
The printer gadget channels data between the USB host and a userspace
program driving the print engine. The user space program reads and
writes the device file /dev/g_printer to receive or send printer data.
It can use ioctl calls to the device file to get or set printer status.

Signed-off-by: Craig W. Nadler <craig@nadler.us>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-02-01 14:34:49 -08:00
Alain Degreffe
60a8fc0171 USB: add iuu_phoenix driver
Signed-off-by: Alain Degreffe <eczema@ecze.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-02-01 14:34:47 -08:00
Alan Stern
3c886c5048 USB: power-management documenation update
This patch (as1014) was partly written by Tilman Schmidt.  It
clarifies the USB power-management documentation by explaining that
when a disconnect occurs, a suspend method call might not be followed
by either a resume or a reset_resume call.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-11-28 13:58:34 -08:00
Simon Arlott
0f035b8e84 spelling fixes: Documentation/
Spelling fixes in Documentation/.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
2007-10-20 01:30:25 +02:00
Alan Stern
cd38c1e1ae USB: documentation for USB power management
This patch (as998) adds documentation on how USB power management
works and how to use it.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12 14:55:34 -07:00
Frank A Kingswood
6ce7610478 USB: Driver for CH341 USB-serial adaptor
This patch implements a USB serial port driver for the Winchiphead
CH341 USB-RS232 Converter. This chip also implements an IEEE 1284
parallel port, I2C and SPI, but that is not supported by the driver.

Signed-off-by: Frank A Kingswood <frank@kingswood-consulting.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12 14:55:29 -07:00
Paolo 'Blaisorblade' Giarrusso
092a212e8e USB: usbmon doc update - mention new wildcard ('0') bus
Update usbmon documentation, mentioning the "zero" (wildcard) bus.
Possibly, in my first hunk, the 'either ... or ...' should be rephrased a bit to
be expressed better.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12 14:55:21 -07:00
Inaky Perez-Gonzalez
732bb9ee81 usb: document device authorization
Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12 14:55:08 -07:00
David Brownell
fbf54dd320 USB: usb/dma doc updates
This patch updates some of the documentation about DMA buffer management
for USB, and ways to avoid extra copying.  Our understanding of the issues
has improved over time.

 - Most drivers should *avoid* the dma-coherent allocators.  There are
   a few exceptions (like the HID driver).

 - Some methods are currently commented out; it seems folk writing
   USB drivers aren't doing performance tuning at that level yet.

 - Just avoid highmem; there's no good way to pass an "I can do highmem
   DMA" capability through a driver stack.  This is easy, everything
   already avoids highmem.  But it'd be nice if x86_32 systems with much
   physical memory could use it directly with network adapters and mass
   storage devices.  (Patch, anyone?)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-12 16:34:42 -07:00
Alan Stern
b41a60eca8 USB: add power/persist device attribute
This patch (as920) adds an extra level of protection to the
USB-Persist facility.  Now it will apply by default only to hubs; for
all other devices the user must enable it explicitly by setting the
power/persist device attribute.

The disconnect_all_children() routine in hub.c has been removed and
its code placed inline.  This is the way it was originally as part of
hub_pre_reset(); the revised usage in hub_reset_resume() is
sufficiently different that the code can no longer be shared.
Likewise, mark_children_for_reset() is now inline as part of
hub_reset_resume().  The end result looks much cleaner than before.

The sysfs interface is updated to add the new attribute file, and
there are corresponding documentation updates.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-12 16:34:30 -07:00
Alan Stern
0458d5b4c9 USB: add USB-Persist facility
This patch (as886) adds the controversial USB-persist facility,
allowing USB devices to persist across a power loss during system
suspend.

The facility is controlled by a new Kconfig option (with appropriate
warnings about the potential dangers); when the option is off the
behavior will remain the same as it is now.  But when the option is
on, people will be able to use suspend-to-disk and keep their USB
filesystems intact -- something particularly valuable for small
machines where the root filesystem is on a USB device!

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-12 16:29:47 -07:00