We don't have to start a transaction in writepage() when all the blocks
are a properly allocated. Even in ordered mode either the data has been
written via write() and they are thus already added to transaction's list
or the data was written via mmap and then it's random in which transaction
they get written anyway.

This should help VM to pageout dirty memory without blocking on transaction
commits.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev: (35 commits)
  [libata] Improve timeout handling
  [libata] Drain data on errors
  pata_sc1200: Activate secondary channel
  pata_artop: Serializing support
  [libata] ahci: correct enclosure LED state save
  [libata] More robust parsing for IDENTIFY DEVICE multi_count field
  sata_mv: fix LED blinking for SoC+NCQ
  sata_mv: optimize IRQ coalescing for 8-port chips
  sata_mv: implement IRQ coalescing (v2)
  sata_mv: cosmetic preparations for IRQ coalescing
  pata-rb532-cf: platform_get_irq() fix ignored failure
  pata_efar: fix *dma_mask
  pata_radisys: fix mwdma_mask to exclude mwdma0
  [libata] convert drivers to use ata.h mode mask defines
  include/linux/ata.h: add some more transfer masks
  ahci: Blacklist HP Compaq 6720s that spins off disks during ACPI power off
  [libata] sata_mv: Implement direct FIS transmission via mv_qc_issue_fis().
  [libata] Export ata_pio_queue_task() so that it can be used from sata_mv.
  [libata] sata_mv: Add a new mv_sff_check_status() function to sata_mv.
  [libata] sata_mv: Tighten up interrupt masking in mv_qc_issue()
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (97 commits)
  USB: qcserial: add device id for HP devices
  USB: isp1760: Add a delay before reading the SKIPMAP registers in isp1760-hcd.c
  USB: allow malformed LANGID descriptors
  USB: pxa27x_udc: typo fixes and code cleanups
  USB: gadget: gadget zero uses new suspend/resume hooks
  USB: gadget: composite device-level suspend/resume hooks
  USB: r8a66597-hcd: suspend/resume support
  USB: more u32 conversion after transfer_buffer_length and actual_length
  USB: Fix cp2101 USB serial device driver termios functions for console use
  USB: CP2101 New Device ID
  USB: ipaq: handle 4 endpoint devices
  USB: S3C: Move usb-control.h to platform include
  USB: ohci-hcd: Add ARCH_S3C24XX to the ohci-s3c2410.c glue
  USB: pedantic: spelling correction in comment for ch9.h
  USB: host: fix sparse warning: Using plain integer as NULL pointer
  USB: ohci-s3c2410: fix name of bus clock
  USB: ohci-s3c2410: remove <mach/hardware.h> include
  USB: serial: rename cp2101 driver to cp210x
  USB: CP2101 Reduce Error Logging
  USB: CP2101 Support AN205 baud rates
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6: (61 commits)
  Dynamic debug: fix pr_fmt() build error
  Dynamic debug: allow simple quoting of words
  dynamic debug: update docs
  dynamic debug: combine dprintk and dynamic printk
  sysfs: fix some bin_vm_ops errors
  kobject: don't block for each kobject_uevent
  sysfs: only allow one scheduled removal callback per kobj
  Driver core: Fix device_move() vs. dpm list ordering, v2
  Driver core: some cleanup on drivers/base/sys.c
  Driver core: implement uevent suppress in kobject
  vcs: hook sysfs devices into object lifetime instead of "binding"
  driver core: fix passing platform_data
  driver core: move platform_data into platform_device
  sysfs: don't block indefinitely for unmapped files.
  driver core: move knode_bus into private structure
  driver core: move knode_driver into private structure
  driver core: move klist_children into private structure
  driver core: create a private portion of struct device
  driver core: remove polling for driver_probe_done(v5)
  sysfs: reference sysfs_dirent from sysfs inodes
  ...

Fixed conflicts in drivers/sh/maple/maple.c manually

* git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6: (53 commits)
  ide: use try_to_identify() in ide_driveid_update()
  ide: clear drive IRQ after re-enabling local IRQs in ide_driveid_update()
  ide: sanitize SELECT_MASK() usage in ide_driveid_update()
  ide: classify device type in do_probe()
  ide: remove broken EXABYTENEST support
  ide: shorten timeout value in ide_driveid_update()
  ide: propagate AltStatus workarounds to ide_driveid_update()
  ide: fix kmalloc() failure handling in ide_driveid_update()
  mn10300: remove <asm/ide.h>
  frv: remove <asm/ide.h>
  ide: remove pciirq argument from ide_pci_setup_ports()
  ide: fix ->init_chipset method to return 'int' value
  ide: remove try_to_identify() wrapper
  ide: remove no longer needed IRQ auto-probing from try_to_identify() (v2)
  ide: remove no longer needed IRQ fallback code from hwif_init()
  amd74xx: remove no longer needed ->init_hwif method
  ide: remove no longer needed IDE_HFLAG[_FORCE]_LEGACY_IRQS
  ide: use ide_pci_is_in_compatibility_mode() in ide_pci_init_{one,two}()
  ide: use pci_get_legacy_ide_irq() in ide_pci_init_{one,two}()
  ide: handle IDE_HFLAG[_FORCE]_LEGACY_IRQS in ide_pci_init_{one,two}()
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (96 commits)
  sh: add support for SMSC Polaris platform
  sh: fix the HD64461 level-triggered interrupts handling
  sh: sh-rtc wakeup support
  sh: sh-rtc invalid time rework
  sh: sh-rtc carry interrupt rework
  sh: disallow kexec virtual entry
  sh: kexec jump: fix for ftrace.
  sh: kexec: Drop SR.BL bit toggling.
  sh: add kexec jump support
  sh: rework kexec segment code
  sh: simplify kexec vbr code
  sh: Flush only the needed range when unmapping a VMA.
  sh: Update debugfs ASID dumping for 16-bit ASID support.
  sh: tlb-pteaex: Kill off legacy PTEA updates.
  sh: Support for extended ASIDs on PTEAEX-capable SH-X3 cores.
  sh: sh7763rdp: Change IRQ number for sh_eth of sh7763rdp
  sh: espt-giga board support
  sh: dma: Make G2 DMA configurable.
  sh: dma: Make PVR2 DMA configurable.
  sh: Move IRQ multi definition of DMAC to defconfig
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw:
  GFS2: Fix freeze issue
  Fix a minor bug in the previous patch
  GFS2: Clean up of glops.c
  GFS2: Fix locking bug in failed shared to exclusive conversion
  GFS2: Pagecache usage optimization on GFS2
  GFS2: fix sparse warning: Should it be static?
  GFS2: fix sparse warnings: constant is so big it is ...
  GFS2: Support quota/noquota mount arguments
  GFS2: Fix alignment issue and tidy gfs2_bitfit
  GFS2: Add a "demote a glock" interface to sysfs
  GFS2: Expose UUID via sysfs/uevent
  GFS2: Support generation of discard requests
  GFS2: Fix deadlock on journal flush
  GFS2: Fix error path ref counting for root inode
  GFS2: Remove unused field from glock
  GFS2: Merge lock_dlm module into GFS2
  GFS2: Remove "double" locking in quota
  GFS2: change gfs2_quota_scan into a shrinker
  GFS2: Bring back lvb-related stuff to lock_nolock to support quotas
  GFS2: Fix remount argument parsing

* git://git.kernel.org/pub/scm/linux/kernel/git/hskinnemoen/avr32-2.6:
  avr32: remove duplicated #include
  avr32: fix out-of-range rjmp instruction on large kernels
  avr32: Fix out-of-range rcalls in large kernels

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6: (430 commits)
  ALSA: hda - Add quirk for Acer Ferrari 5000
  ALSA: hda - Use cached calls to get widget caps and pin caps
  ALSA: hda - Don't create empty/single-item input source
  ALSA: hda - Fix the wrong pin-cap check in patch_realtek.c
  ALSA: hda - Cache pin-cap values
  ALSA: hda - Avoid output amp manipulation to digital mic pins
  ALSA: hda - Add function id to proc output
  ALSA: pcm - Safer boundary checks
  ALSA: hda - Detect digital-mic inputs on ALC663 / ALC272
  ALSA: sound/ali5451: typo: s/resouces/resources/
  ALSA: hda - Don't show the current connection for power widgets
  ALSA: Fix wrong pointer to dev_err() in arm/pxa2xx-ac97-lib.c
  ASoC: Declare Headset as Mic and Headphone widgets for SDP3430
  ASoC: OMAP: N810: Add more jack functions
  ASoC: OMAP: N810: Mark not connected input pins
  ASoC: Add FLL support for WM8400
  ALSA: hda - Don't reset stream at each prepare callback
  ALSA: hda - Don't reset BDL unnecessarily
  ALSA: pcm - Fix delta calculation at boundary overlap
  ALSA: pcm - Reset invalid position even without debug option
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (29 commits)
  crypto: sha512-s390 - Add missing block size
  hwrng: timeriomem - Breaks an allyesconfig build on s390:
  nlattr: Fix build error with NET off
  crypto: testmgr - add zlib test
  crypto: zlib - New zlib crypto module, using pcomp
  crypto: testmgr - Add support for the pcomp interface
  crypto: compress - Add pcomp interface
  netlink: Move netlink attribute parsing support to lib
  crypto: Fix dead links
  hwrng: timeriomem - New driver
  crypto: chainiv - Use kcrypto_wq instead of keventd_wq
  crypto: cryptd - Per-CPU thread implementation based on kcrypto_wq
  crypto: api - Use dedicated workqueue for crypto subsystem
  crypto: testmgr - Test skciphers with no IVs
  crypto: aead - Avoid infinite loop when nivaead fails selftest
  crypto: skcipher - Avoid infinite loop when cipher fails selftest
  crypto: api - Fix crypto_alloc_tfm/create_create_tfm return convention
  crypto: api - crypto_alg_mod_lookup either tested or untested
  crypto: amcc - Add crypt4xx driver
  crypto: ansi_cprng - Add maintainer
  ...

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq: (35 commits)
  [CPUFREQ] Prevent p4-clockmod from auto-binding to the ondemand governor.
  [CPUFREQ] Make cpufreq-nforce2 less obnoxious
  [CPUFREQ] p4-clockmod reports wrong frequency.
  [CPUFREQ] powernow-k8: Use a common exit path.
  [CPUFREQ] Change link order of x86 cpufreq modules
  [CPUFREQ] conservative: remove 10x from def_sampling_rate
  [CPUFREQ] conservative: fixup governor to function more like ondemand logic
  [CPUFREQ] conservative: fix dbs_cpufreq_notifier so freq is not locked
  [CPUFREQ] conservative: amend author's email address
  [CPUFREQ] Use swap() in longhaul.c
  [CPUFREQ] checkpatch cleanups for acpi-cpufreq
  [CPUFREQ] powernow-k8: Only print error message once, not per core.
  [CPUFREQ] ondemand/conservative: sanitize sampling_rate restrictions
  [CPUFREQ] ondemand/conservative: deprecate sampling_rate{min,max}
  [CPUFREQ] powernow-k8: Always compile powernow-k8 driver with ACPI support
  [CPUFREQ] Introduce /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_transition_latency
  [CPUFREQ] checkpatch cleanups for powernow-k8
  [CPUFREQ] checkpatch cleanups for ondemand governor.
  [CPUFREQ] checkpatch cleanups for powernow-k7
  [CPUFREQ] checkpatch cleanups for speedstep related drivers.
  ...

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6: (71 commits)
  SELinux: inode_doinit_with_dentry drop no dentry printk
  SELinux: new permission between tty audit and audit socket
  SELinux: open perm for sock files
  smack: fixes for unlabeled host support
  keys: make procfiles per-user-namespace
  keys: skip keys from another user namespace
  keys: consider user namespace in key_permission
  keys: distinguish per-uid keys in different namespaces
  integrity: ima iint radix_tree_lookup locking fix
  TOMOYO: Do not call tomoyo_realpath_init unless registered.
  integrity: ima scatterlist bug fix
  smack: fix lots of kernel-doc notation
  TOMOYO: Don't create securityfs entries unless registered.
  TOMOYO: Fix exception policy read failure.
  SELinux: convert the avc cache hash list to an hlist
  SELinux: code readability with avc_cache
  SELinux: remove unused av.decided field
  SELinux: more careful use of avd in avc_has_perm_noaudit
  SELinux: remove the unused ae.used
  SELinux: check seqno when updating an avc_node
  ...

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  MIPS: R2: Fix problem with code that incorrectly modifies ebase.
  MIPS: Change {set,clear,change}_c0_<foo> to return old value.
  MIPS: compat: Remove duplicated #include
  MIPS: VR5500: Enable prefetch
  MIPS: Fix oops in dma_unmap_page on not coherent mips platforms

Enlarge default dirty ratios from 5/10 to 10/20.  This fixes [Bug
#12809] iozone regression with 2.6.29-rc6.

The iozone benchmarks are performed on a 1200M file, with 8GB ram.

  iozone -i 0 -i 1 -i 2 -i 3 -i 4 -r 4k -s 64k -s 512m -s 1200m -b tmp.xls
  iozone -B -r 4k -s 64k -s 512m -s 1200m -b tmp.xls

The performance regression is triggered by commit 1cf6e7d8(mm: task
dirty accounting fix), which makes more correct/thorough dirty
accounting.

The default 5/10 dirty ratios were picked (a) with the old dirty logic
and (b) largely at random and (c) designed to be aggressive.  In
particular, that (a) means that having fixed some of the dirty
accounting, maybe the real bug is now that it was always too aggressive,
just hidden by an accounting issue.

The enlarged 10/20 dirty ratios are just about enough to fix the regression.

[ We will have to look at how this affects the old fsync() latency issue,
  but that probably will need independent work.  - Linus ]

Cc: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reported-by: "Lin, Ming M" <ming.m.lin@intel.com>
Tested-by: "Lin, Ming M" <ming.m.lin@intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Change the default behaviour of the kernel to use relatime for all
filesystems. This can be overridden with the "strictatime" mount
option.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add support for explicitly requesting full atime updates. This makes it
possible for kernels to default to relatime but still allow userspace to
override it.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Allow atime to be updated once per day even with relatime. This lets
utilities like tmpreaper (which delete files based on last access time)
continue working, making relatime a plausible default for distributions.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Valerie Aurora Henson <vaurora@redhat.com>
Acked-by: Alan Cox <alan@redhat.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

On a timeout call a device specific handler early in the recovery so that
we can complete and process successful commands which timed out due to IRQ
loss or the like rather more elegantly.

[Revised to exclude the timeout handling on a few devices that inherit from
 SFF but are not SFF enough to use the default timeout handler]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

If the device is signalling that there is data to drain after an error we
should read the bytes out and throw them away. Without this some devices
and controllers get wedged and don't recover.

Based on earlier work by Mark Lord
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Implement serialize and turn on slave channel
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Enable both ports on the 6210 and serialize them
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

ahci_transmit_led_message saves off the led_state
with a value that includes the port number OR'd
in, this incorrect value maybe reported back
in ahci_led_store.

For instance, if you turn off all the leds for
port 1 and cat the value back it will report 1
instead of 0.

# echo 0 > /sys/class/scsi_host/host1/em_message
# cat /sys/class/scsi_host/host1/em_message
1
Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Make libata more robust when parsing the multi_count
field from a drive's identify data.  This prevents us from
attempting to use dubious multi_count values ad infinitum.

Reset dev->multi_count to zero and reprobe it each time
through this routine, as it can change on device reset.

Also ensure that the reported "maximum" value is valid
and is a power of two, and that the reported "count" value
is valid and also a power of two.  And that the "count"
value is not greater than the "maximum" value.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

For Marvell SoC chips, the HDD LED does not blink when there is
disk I/O if NCQ is enabled. Add a quirk that enables blink mode for
the LED while NCQ is enabled on any port of a SoC host controller.
Normal LED function is restored when NCQ is not enabled on any port.

The code to enable the blink mode is based on earlier code
and suggestions from Frans Pop, Saeed Bishara, and possibly others.
Signed-off-by: Mark Lord <mlord@pobox.com>
Tested-by: Frans Pop <elendil@planet.nl>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Enable use of the "all ports" IRQ coalescing optimization
for GEN_II / GEN_IIE chips that have dual host-controllers (8-ports).
Currently only the 6081 chip qualifies, but other chips may come along someday.

Rather than each half of the chip having to satisfy a local set of coalescing thresholds,
use of this feature groups all ports together under a single set of thresholds.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Add IRQ coalescing to sata_mv (off by default).

This feature can reduce total interrupt overhead for RAID setups
in some situations, by deferring the interrupt signal until one or both of:

 a) a specified io_count (completed SATA commands) is achieved, or
 b) a specified time interval elapses after an IO completion.

For now, module parameters are used to set the irq_coalescing_io_count
and irq_coalescing_usecs (timeout) globally.  These may eventually
be supplemented with sysfs attributes, so that thresholds can be set
on-the-fly and on a per-chip (or even per-host_controller) basis.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Various cosmetic changes in preparation for the IRQ coalescing feature.

Note that the various MV_IRQ_COAL_* definitions are restored/renamed
in the folloup patch which adds IRQ coalescing to the driver.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

platform_get_irq() can return -ENXIO, but since 'irq' is an
unsigned int, it does not show when the IRQ resource wasn't found.
Make irq an int so that we can use a single variable to test the
platform_get_irq() return value.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Phil Sutter <n0-1@freewrt.org>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

According to Alan:
>and yes the EFAR does UDMA66.

mwdma:
>Yep - wrong comment. The EFAR is a sort of clone of the PIIX and I
>copied the comment while EFAR don't appear to have copied the
>limitation
Signed-off-by: Erik Inge Bolsø <knan-lkml@anduin.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

As noted by Alan:
>Your suspicions are correct here btw - the device can only do MWDMA1 and
>MWDMA2 (much like some PIIX devices)
Signed-off-by: Erik Inge Bolsø <knan-lkml@anduin.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

No functional changes in this patch.
Signed-off-by: Erik Inge Bolsø <knan-lkml@anduin.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Signed-off-by: Erik Inge Bolsø <knan-lkml@anduin.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Blacklist HP Compaq 6720s so that it doesn't play a "spin down,
spin up, spin down" ping-pong with the hard disk during system
power off.
Signed-off-by: Maciej Rutecki <maciej.rutecki@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

This is initially needed to work around NCQ errata,
whereby the READ_LOG_EXT command sometimes fails
when issued in the traditional (sff) fashion.

Portions of this code will likely be reused for
implementation of the target mode feature later on.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

This is necessary for use with the upcoming "mv_qc_issue_fis()" patch,
but is being added separately here for easier code review.

When using command issue via the "mv_qc_issue_fis()" mechanism,
the initial ATA_BUSY bit does not show in the ATA status (shadow) register.
This can confuse libata!  So here we add a hook to fake ATA_BUSY
for that situation, until the first time a BUSY, DRQ, or ERR bit is seen.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

so that it doesn't miss any protocols.  Handle future cases where a
qc is specially marked for polled issue or where a particular chip
version prefers interrupts over polling for PIO.

This mimics the polling decision logic from ata_sff_qc_issue().
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

This also gets rid of any need for mv_mode_filter().

Using basic DMA on GEN_IIE requires setting an undocumented
bit in an undocumented register.  For safety, we clear that
bit again when switching back to EDMA mode.

To avoid a performance penalty when switching modes,
we cache the register in port_priv, as already done for other regs.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Maintain a local (mv_port_priv) cache of frequently accessed registers,
to avoid having to re-read them (very slow) on every transistion
between EDMA and non-EDMA modes.  This speeds up things like
flushing the drive write cache, and anything using basic DMA transfers.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

There's no need to turn off intx explicitly on msi enable.  This is
automatically handled by pci.  Drop it.

This might be needed on machines if the BIOS turns intx off during
boot.  However, there's no evidence of such behavior for ahci and
the only such case seems to be ICH5 PATA according to ata_piix.
Also, given the way ahci operates, it's highly unlikely BIOS ever
disables IRQ for the controller.  However, as this change has slight
possibility of introducing failure, please schedule it for #upstream.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>