This patch (as1003) changes uhci-hcd to treat the URB_ISO_ASAP flag
the same as other host controller drivers, namely, to schedule an Iso
URB for the first available time slot that hasn't already expired.
URBs in which the flag isn't set will be scheduled for the first slot
following the last URB, even if it has expired.
This fixes a problem reported by Martin Bachem.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as979) removes the last vestiges of urb->status from the
host controller drivers and the root-hub emulator. Now the field
doesn't get set until just before the URB's completion routine is
called.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
CC: Olav Kongas <ok@artecdesign.ee>
CC: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
CC: Tony Olech <tony.olech@elandigitalsystems.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as970) adds a new urb->unlinked field, which is used to
store the status of unlinked URBs since we can't use urb->status for
that purpose any more. To help simplify the HCDs, usbcore will check
urb->unlinked before calling the completion handler; if the value is
set it will automatically override the status reported by the HCD.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
CC: Olav Kongas <ok@artecdesign.ee>
CC: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
CC: Tony Olech <tony.olech@elandigitalsystems.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as969) continues the ongoing changes to the way HCDs
report URB statuses. The programming interface has been simplified by
making usbcore responsible for clearing urb->hcpriv and for setting
-EREMOTEIO status when an URB with the URB_SHORT_NOT_OK flag ends up
as a short transfer.
By moving the work out of the HCDs, this removes a fair amount of
repeated code.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
CC: Olav Kongas <ok@artecdesign.ee>
CC: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
CC: Tony Olech <tony.olech@elandigitalsystems.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (968) changes the way uhci-hcd reports status for
Isochronous URBs. Until now urb->status has been set to the last
detected error code. But other HCDs don't do this; they leave the
status set to 0 and report errors only in the individual iso packet
descriptors. So this patch removes the extra computation and makes
uhci-hcd behave like the others.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as954) implements a suggestion of David Brownell's. Now
the host controller drivers are responsible for linking and unlinking
URBs to/from their endpoint queues. This eliminates the possiblity of
strange situations where usbcore thinks an URB is linked but the HCD
thinks it isn't. It also means HCDs no longer have to check for URBs
being dequeued before they were fully enqueued.
In addition to the core changes, this requires changing every host
controller driver and the root-hub URB handler. For the most part the
required changes are fairly small; drivers have to call
usb_hcd_link_urb_to_ep() in their urb_enqueue method,
usb_hcd_check_unlink_urb() in their urb_dequeue method, and
usb_hcd_unlink_urb_from_ep() before giving URBs back. A few HCDs make
matters more complicated by the way they split up the flow of control.
In addition some method interfaces get changed. The endpoint argument
for urb_enqueue is now redundant so it is removed. The unlink status
is required by usb_hcd_check_unlink_urb(), so it has been added to
urb_dequeue.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
CC: Olav Kongas <ok@artecdesign.ee>
CC: Tony Olech <tony.olech@elandigitalsystems.com>
CC: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
It has recently been pointed out that short control transfers should
have a status stage, even if they generate an error because
URB_SHORT_NOT_OK was set. This patch (as935) changes uhci-hcd to
enable the status stage when this happens.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as872) adds some WARN_ON()s to various error checks which
are never supposed to fail. Unsettlingly, one of them has shown up in
a user's log! Maybe making the warning more visible and having the
call-stack information available will help pinpoint the source of the
problem.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as871) fixes a problem introduced by an earlier change.
It turns out that some systems really do need to have a terminating
skeleton QH present whenever FSBR is on. I don't know any way to tell
which systems do need it and which don't; the easiest answer is to
have it there always.
This fixes the NumLock-hang bug reported by Jiri Slaby.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as856) attempts to improve the performance of uhci-hcd by
removing the asynchronous skeleton Queue Headers. They don't contain
any useful information but the controller has to read through them at
least once every millisecond, incurring a non-zero DMA overhead.
Now all the asynchronous queues are combined, along with the period-1
interrupt queue, into a single list with a single skeleton QH. The
start of the low-speed control, full-speed control, and bulk sublists
is determined by linear search. Since there should rarely be more
than a couple of QHs in the list, the searches should incur a much
smaller total load than keeping the skeleton QHs.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as855) adds some convenience macros to uhci-hcd, to help
simplify the code for computing hardware DMA pointers.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Replace appropriate pairs of "kmem_cache_alloc()" + "memset(0)" with the
corresponding "kmem_cache_zalloc()" call.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Roland McGrath <roland@redhat.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Greg KH <greg@kroah.com>
Acked-by: Joel Becker <Joel.Becker@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Jan Kara <jack@ucw.cz>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch (as840) fixes the bandwidth allocation mechanism in
uhci-hcd. It has never worked correctly.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Isochronous queues don't need a dummy TD because the Queue Header
isn't managed by the hardware. This patch (as836) removes the
unnecessary dummy TDs.
The patch also fixes a long-standing typo in a comment (a "don't" was
missing -- potentially very confusing!).
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
SLAB_ATOMIC is an alias of GFP_ATOMIC
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
When skipping to the last TD of an URB, go to the _last_ entry in the
list instead of the _first_ entry (as780). This fixes Bugzilla #6747
and possibly others.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Unlike other sorts of endpoint queues, Isochronous queues don't stop
when an error is encountered. This patch (as772) fixes the scanning
routine in uhci-hcd, to make it keep on going when it finds an Iso
error.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Apparently some UHCI controllers change the value of the Short Packet
Detect (SPD) bit in the TD status word -- presumably when they receive a
short packet. This patch (as759) changes uhci-hcd to avoid assuming
that the bit is unchanged; in fact, the driver no longer looks at SPD at
all.
This fixes the second problem reported in Bugzilla #6752.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as707) improves the FSBR operation in uhci-hcd by turning it
off more quickly when it isn't needed. FSBR puts a noticeable load on a
computer's PCI bus, so it should be disabled as soon as possible when it
isn't in use. The patch leaves it running for only 10 ms after the last
URB stops using it, on the theory that this should be long enough for a
driver to submit another URB if it wants keep FSBR going.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as705) contains a small set of updates for uhci-hcd written
mostly by Dave Brownell:
* Root hub suspend messages come out labeled as root hub messages;
PCI messages should only come out when the pci device suspends.
* Rename the reset() method to better match its init() role
* Behave more like the other HCDs by returning -ESHUTDOWN for root-hub
suspend/resume errors.
* When an URB fails, associate the message with the usb device not
the host controller (it still hides endpoint and direction)
From: David Brownell <david-b@pacbell.net>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as690) does the same thing for ISO TDs as as680 did for
non-ISO TDs: free them as they are used rather than all at once when an
URB is complete. At the same time it fixes a minor buglet (I'm not
aware of it ever affecting anyone): An ISO TD should be retired when its
frame is over, regardless of whether or not the hardware has marked it
inactive.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as689) stores the period for periodic transfers (interrupt
and ISO) in the queue header. This is necessary for proper bandwidth
tracking (not yet implemented). It also makes the scheduling of ISO
transfers a bit more rigorous, with checks for out-of-bounds frame
numbers.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as688) fixes a small race in uhci-hcd. Because ISO queues
aren't controlled by queue headers, they can't be unlinked. Only
individual URBs can. So whenever multiple ISO URBs are dequeued, it's
necessary to make sure the hardware is done with each one. We can't
assume that dequeuing the first URB will suffice to unlink the entire
queue.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Some old Intel UHCI controllers have a bug that has shown up in a few
systems (the PIIX3 "Neptune" chip set). Until now there has not been
any simple way to work around the bug, but the lastest changes in
uhci-hcd have made it easy. This patch (as684) adds the work-around.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as683) re-implements Full-Speed Bandwidth Reclamation (FSBR)
properly. It keeps track of which endpoint queues have advanced, and
when none have advanced for a sufficiently long time, FSBR is turned
off. The next TD on each of the non-moving queues is modified to
generate an interrupt on completion, so that FSBR can be re-enabled as
soon as the hardware starts to make some progress.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as682) gets rid of the TD-removal list in uhci-hcd. It is
no longer needed because now TDs are not freed until we know the
hardware isn't using them. It also simplifies the code for adding and
removing TDs to/from URBs.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as681) moves some code for cleaning up after unlinked URBs
out of the general completion pathway into the unlinking pathway.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as680) frees non-isochronous TDs as they are used, rather
than all at once when an URB is complete. Although not a terribly
important change in itself, it opens the door to a later enhancement
that will reduce storage requirements by allocating only a limited
number of TDs at any time for each endpoint queue.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as679) combines the result routine for Control URBs with the
routine for Bulk/Interrupt URBs. Along the way I eliminated the
debugging printouts for Control transfers unless the debugging level is
set higher than 1. I also eliminated a long-unused (#ifdef'ed-out)
section that works around some buggy old APC BackUPS devices.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as676) fixes a small bug in uhci-hcd's enqueue routine. When
an URB is unlinked or gets an error and the completion handler queues
another URB for the same endpoint, the queue shouldn't be allowed to start
up again until the handler returns. Not even if the new URB is the only
one on its queue.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as675) simplifies uhci-hcd slightly by storing each endpoint's
type in the corresponding Queue Header structure.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as640) removes several put_device and the corresponding
get_device calls from the USB core and HCDs. Some of the puts were done
in atomic contexts, and none of them are needed since the core now
guarantees that every endpoint will be disabled and every URB completed
before a USB device is released.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
A recent update to the uhci-hcd driver invoked the list_prepare_entry
macro incorrectly. This patch (as646) corrects it.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Even when the URB_SHORT_NOT_OK flag is set, a short transfer shouldn't
generate a debugging log message. Especially not one with the confusing
claim that the transfer "failed with status 0". This patch (as627)
fixes that behavior in uhci-hcd.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as626) makes some improvements to the debugging code in
uhci-hcd. The main change is that now the code won't get compiled if
CONFIG_USB_DEBUG isn't set. But there are other changes too, like
adding a missing .owner field and printing a debugging dump if the
controller dies.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
As part of reorienting uhci-hcd away from URBs and toward endpoint
queues, this patch (as625) eliminates the driver's main list of URBs.
The list wsa used mainly in checking for URB completions; now the driver
goes through the list of active endpoints and checks the members of the
queues.
As a side effect, I had to remove the code that looks for FSBR timeouts.
For now, FSBR will remain on so long as any URBs on a full-speed control
or bulk queue request it, even if the queue isn't advancing. A later
patch can add more intelligent handling. This isn't a huge drawback;
it's pretty rare for an URB to get stuck for more than a fraction of a
second. (And it will help the people trying to use those insane HP USB
devices.)
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as624) fixes a hardware race in uhci-hcd by adding a dummy
TD to the end of each endpoint's queue. Without the dummy the host
controller will effectively turn off the queue when it reaches the end,
which happens asynchronously. This leads to a potential problem when
new transfer descriptors are added to the end of the queue; they may
never get used.
With a dummy TD present the controller never turns off the queue;
instead it just stops at the dummy and leaves the queue on but inactive.
When new TDs are added to the end of the queue, the first new one gets
written over the dummy. Thus there's never any question about whether
the queue is running or needs to be restarted.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as623) changes the uhci-hcd driver to make it use one QH per
device endpoint, instead of a QH per URB as it does now. Numerous areas
of the code are affected by this. For example, the distinction between
"queued" URBs and non-"queued" URBs no longer exists; all URBs belong to
a queue and some just happen to be at the queue's head.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Some USB devices don't enumerate well with FSBR turned on. This patch
keeps devices on the low-speed part of the schedule (which doesn't use
FSBR) until they have been fully configured.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as615b) edits a large number of comments in the uhci-hcd code,
mainly removing excess apostrophes.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as616) changed the uhci_explen macro in uhci-hcd.h so that
it now accepts the desired length, rather than length - 1 with special
handling for 0. This also fixes a minor bug that would show up only
when a driver submits a 0-length bulk URB.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The uhci-hcd driver is fairly lax about the way it handles isochronous
transfers. This patch (as579) improves it in three respects:
TDs for a new URB aren't added to the schedule until all of
them have been allocated. This way there's no risk of the
controller executing some of them when an allocation fails.
TDs for an unlinked URB are removed from the schedule as soon
as the URB is unlinked, rather than waiting until the URB is
given back. This way there's no risk of the controller still
executing a TD after the URB completes.
The urb->error_count values are now reported correctly.
Although since they aren't used in any drivers except for
debug messages in the system log, probably nobody cares.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as563) splits the physical and logical framelist arrays in
uhci-hcd into two separate pieces. This will allow slightly better memory
utilization, since each piece is no larger than a single page whereas
before the whole thing was a little bigger than two pages. It also allows
the logical array to be allocated in non-DMA-coherent memory.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as562) removes from the uhci-hcd driver a few unused fields
and some unnecessary tests against NULL and assignments to NULL. In fact
it wasn't until fairly recently that the tests became unnecessary.
Before last winter it was possible that the driver's stop() routine would
get called even if the start() routine returned an error, but now that
can't happen. Hence there's no longer any need to check for partial
initialization.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as558) removes from the UHCI driver a kernel timer used for
checking Full Speed Bandwidth Reclamation (FSBR). The checking can be
done during normal root-hub polling; it doesn't need a separate timer.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Greg,
This patch fixes the kmalloc() flags argument type in USB
subsystem; hopefully all of its occurences. The patch was
made against patch-2.6.12-git2 from Jun 20.
Cleanup of flags for kmalloc() in USB subsystem.
Signed-off-by: Olav Kongas <ok@artecdesign.ee>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch simplifies the uhci-hcd driver by removing the device pointer
currently stored in the QH and TD structures. Those pointers weren't
being used for anything other than to increment the device's reference
count, which is unnecessary since the device is used only when an URB
completes, and outstanding URBs take their own reference to the device.
As a useful side effect, this change means that uhci-hcd no longer needs
to have the root-hub device available in the start routine.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch, which has as478b as a prerequisite, enables the uhci-hcd
driver to take advantage of root-hub IRQs rather than polling during the
time it is suspended. (Unfortunately the hardware doesn't support
port-change interrupts while the controller is running.) It also turns
off the driver's private timer while the controller is suspended, as it
isn't needed then. The combined elimination of polling interrupts and
timer interrupts ought to be enough to allow some systems to save a
noticeable amount of power while they are otherwise idle.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
