Fixes a hang when booting as dom0 under Xen, when jiffies can be
quite large by the time the kernel init gets this far.
Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
[jbeulich@novell.com: !time_after() -> time_before_eq() as suggested by Jiri Slaby]
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit bb758e9637 removed snd_hrtimer_callback() from the hardware
interrupt handler, thus moving it into a tasklet, but did not tell the
ALSA timer framework about this, so the timer handling would now be done
in the ALSA timer tasklet scheduled from another tasklet.
To fix this, add the flag to tell the ALSA timer framework that the
timer handler is already being invoked in a tasklet.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
If a timer interrupt was delayed too much, hrtimer_forward_now() will
forward the timer expiry more than once. When this happens, the
additional number of elapsed ALSA timer ticks must be passed to
snd_timer_interrupt() to prevent the ALSA timer from falling behind.
This mostly fixes MIDI slowdown problems on highly-loaded systems with
badly behaved interrupt handlers.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Reported-and-tested-by: Arthur Marsh <arthur.marsh@internode.on.net>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
According to the reporter, node 0x15 needs to be muted for subwoofer
to stop sounding. This pin is marked as unused by BIOS, so fix that.
BugLink: http://bugs.launchpad.net/bugs/715877
Cc: stable@kernel.org (2.6.37+)
Reported-by: Hans Peter
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
When an empty string is passed to patch option, the driver should
ignore it. Otherwise it gets an error by trying to load it.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Since tail is the previous fp - 1, we need to compare the new fp with tail + 1
to ensure that we don't end up passing in the same tail again, in order to
avoid a potential infinite loop in the perf interrupt handler (which has been
observed to occur). A similar fix seems to be needed in the OProfile code.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
With certain configurations, we inline the unlock functions in modules,
which results in SMP alternatives being created in modules. We need to
fix those up when loading a module to prevent undefined instruction
faults.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Jeff Moyer reported these messages:
Warning: ... trying to fall back to cpu-clock-ticks
couldn't open /proc/-1/status
couldn't open /proc/-1/maps
[ls output]
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.008 MB perf.data (~363 samples) ]
That lead me and David Ahern to see that something was fishy on the thread
synthesizing routines, at least for the case where the workload is started
from 'perf record', as -1 is the default for target_tid in 'perf record --tid'
parameter, so somehow we were trying to synthesize the PERF_RECORD_MMAP and
PERF_RECORD_COMM events for the thread -1, a bug.
So I investigated this and noticed that when we introduced support for
recording a process and its threads using --pid some bugs were introduced and
that the way to fix it was to instead of passing the target_tid to the event
synthesizing routines we should better pass the thread_map that has the list of
threads for a --pid or just the single thread for a --tid.
Checked in the following ways:
On a 8-way machine run cyclictest:
[root@emilia ~]# perf record cyclictest -a -t -n -p99 -i100 -d50
policy: fifo: loadavg: 0.00 0.13 0.31 2/139 28798
T: 0 (28791) P:99 I:100 C: 25072 Min: 4 Act: 5 Avg: 6 Max: 122
T: 1 (28792) P:98 I:150 C: 16715 Min: 4 Act: 6 Avg: 5 Max: 27
T: 2 (28793) P:97 I:200 C: 12534 Min: 4 Act: 5 Avg: 4 Max: 8
T: 3 (28794) P:96 I:250 C: 10028 Min: 4 Act: 5 Avg: 5 Max: 96
T: 4 (28795) P:95 I:300 C: 8357 Min: 5 Act: 6 Avg: 5 Max: 12
T: 5 (28796) P:94 I:350 C: 7163 Min: 5 Act: 6 Avg: 5 Max: 12
T: 6 (28797) P:93 I:400 C: 6267 Min: 4 Act: 5 Avg: 5 Max: 9
T: 7 (28798) P:92 I:450 C: 5571 Min: 4 Act: 5 Avg: 5 Max: 9
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.108 MB perf.data (~4719 samples) ]
[root@emilia ~]#
This will create one extra thread per CPU:
[root@emilia ~]# tuna -t cyclictest -CP
thread ctxt_switches
pid SCHED_ rtpri affinity voluntary nonvoluntary cmd
28825 OTHER 0 0xff 2169 671 cyclictest
28832 FIFO 93 6 52338 1 cyclictest
28833 FIFO 92 7 46524 1 cyclictest
28826 FIFO 99 0 209360 1 cyclictest
28827 FIFO 98 1 139577 1 cyclictest
28828 FIFO 97 2 104686 0 cyclictest
28829 FIFO 96 3 83751 1 cyclictest
28830 FIFO 95 4 69794 1 cyclictest
28831 FIFO 94 5 59825 1 cyclictest
[root@emilia ~]#
So we should expect only samples for the above 9 threads when using the
--dump-raw-trace|-D perf report switch to look at the column with the tid:
[root@emilia ~]# perf report -D | grep RECORD_SAMPLE | cut -d/ -f2 | cut -d: -f1 | sort | uniq -c
629 28825
110 28826
491 28827
308 28828
198 28829
621 28830
225 28831
203 28832
89 28833
[root@emilia ~]#
So for workloads started by 'perf record' seems to work, now for existing workloads,
just run cyclictest first, without 'perf record':
[root@emilia ~]# tuna -t cyclictest -CP
thread ctxt_switches
pid SCHED_ rtpri affinity voluntary nonvoluntary cmd
28859 OTHER 0 0xff 594 200 cyclictest
28864 FIFO 95 4 16587 1 cyclictest
28865 FIFO 94 5 14219 1 cyclictest
28866 FIFO 93 6 12443 0 cyclictest
28867 FIFO 92 7 11062 1 cyclictest
28860 FIFO 99 0 49779 1 cyclictest
28861 FIFO 98 1 33190 1 cyclictest
28862 FIFO 97 2 24895 1 cyclictest
28863 FIFO 96 3 19918 1 cyclictest
[root@emilia ~]#
and then later did:
[root@emilia ~]# perf record --pid 28859 sleep 3
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.027 MB perf.data (~1195 samples) ]
[root@emilia ~]#
To collect 3 seconds worth of samples for pid 28859 and its children:
[root@emilia ~]# perf report -D | grep RECORD_SAMPLE | cut -d/ -f2 | cut -d: -f1 | sort | uniq -c
15 28859
33 28860
19 28861
13 28862
13 28863
10 28864
11 28865
9 28866
255 28867
[root@emilia ~]#
Works, last thing is to check if looking at just one of those threads also works:
[root@emilia ~]# perf record --tid 28866 sleep 3
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.006 MB perf.data (~242 samples) ]
[root@emilia ~]# perf report -D | grep RECORD_SAMPLE | cut -d/ -f2 | cut -d: -f1 | sort | uniq -c
3 28866
[root@emilia ~]#
Works too.
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
amd64_debug_display_dimm_sizes() reports the distribution of the DIMMs
on each DRAM controller and its chip select sizes. Thus, the last don't
have anything to do with whether we're running in ganged DCT mode or not
- their sizes don't change all of a sudden. Fix that by removing the
ganged-check and dump DCT0's config for DCT1 when in ganged mode since
they're identical.
Reported-and-tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
SWP emulation requires that CPU domain support is disabled in order to
work safely. Make that explicit in the kernel configuration to prevent
illegal configurations being generated.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Additionally doing things conditionally upon smp_processor_id()
being zero is generally a bad idea, as this means CPU 0 cannot
be offlined and brought back online later again.
While there may be other places where this is done, I think adding
more of those should be avoided so that some day SMP can really
become "symmetrical".
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
LKML-Reference: <4D525C7E0200007800030EE1@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
During boot if the hardlockup detector fails to initialize, it
complains very loudly. Some failures should be expected under
certain situations, ie no lapics, or resource in-use. Tone
those error messages down a bit. Keep the rest at a high level.
Reported-by: Paul Bolle <pebolle@tiscali.nl>
Tested-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1297278153-21111-1-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In x25_link_free(), we destroy 'nb' before dereferencing
'nb->dev'. Don't do this, because 'nb' might be freed
by then.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Tested-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Follow-on patch to 7e90d705 which is already in Steve's tree...
The check for tcpStatus == CifsGood is not meaningful since it doesn't
indicate whether the NEGOTIATE request has been done. Also, clarify
why we're checking for maxBuf == 0.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
* 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6:
deb-pkg: Fix building outside of source tree (O=...).
deb-pkg: Use $SRCARCH for include path
Previous patch "[PATCH 1/3] pch_can: fix 800k comms issue" is wrong.
I should have modified tseg1_min not tseg2_min.
This patch reverts tseg2_min to 1 and set tseg1_min to 2.
Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some cases try to modify const strings, and in any event the
CVS revision strings have not changed in over ten years making
these printouts completely worthless.
Just kill all of this stuff off.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
I2C address range included 0x2a, which the chips do not support.
Replace with 0x29 which is supported but was missing.
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
LM64 has 16 degrees Celsius temperature offset on all
remote sensor registers.
This was not considered When LM64 support was added to lm63.c.
Signed-off-by: Dirk Eibach <eibach@gdsys.de>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: stable@kernel.org
From: Randy Dunlap <randy.dunlap@oracle.com>
softing_cs.c uses kzalloc & kfree, so it needs to include linux/slab.h.
drivers/net/can/softing/softing_cs.c:234: error: implicit declaration of function 'kfree'
drivers/net/can/softing/softing_cs.c:271: error: implicit declaration of function 'kzalloc'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This driver will be in a deadlock, When the rx offload is set by ethtool.
The pch_gbe_reinit_locked function was modified.
Signed-off-by: Toshiharu Okada <toshiharu-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
virtio: console: Update Copyright
virtio: console: Wake up outvq on host notifications
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
cdrom: support devices that have check_events but not media_changed
cfq-iosched: Don't wait if queue already has requests.
blkio-throttle: Avoid calling blkiocg_lookup_group() for root group
cfq: rename a function to give it more appropriate name
cciss: make cciss_revalidate not loop through CISS_MAX_LUNS volumes unnecessarily.
drivers/block/aoe/Makefile: replace the use of <module>-objs with <module>-y
loop: queue_lock NULL pointer derefence in blk_throtl_exit
drivers/block/Makefile: replace the use of <module>-objs with <module>-y
blktrace: Don't output messages if NOTIFY isn't set.
* 'for-linus' of git://neil.brown.name/md:
FIX: md: process hangs at wait_barrier after 0->10 takeover
md_make_request: don't touch the bio after calling make_request
md: Don't allow slot_store while resync/recovery is happening.
md: don't clear curr_resync_completed at end of resync.
md: Don't use remove_and_add_spares to remove failed devices from a read-only array
Add raid1->raid0 takeover support
md: Remove the AllReserved flag for component devices.
md: don't abort checking spares as soon as one cannot be added.
md: fix the test for finding spares in raid5_start_reshape.
md: simplify some 'if' conditionals in raid5_start_reshape.
md: revert change to raid_disks on failure.
In zram_read() and zram_write() we were not incrementing the
index number and thus were reading/writing values from/to
incorrect sectors on zram disk, resulting in data corruption.
Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The ni_tio and ni_tio modules do not depend on the 8255 module, but the
ni_atmio, ni_mio_cs and ni_pcimio modules do need the 8255 module. The
ni_pcimio module also needs the comedi_fc module.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
As mentioned by W. Trevor King on the devel@linuxdriverproject.org list
on "Thu, 27 Jan 2011 18:52:15 -0500", "Message-ID:
<20110127235214.GA5107@thialfi.dhcp.drexel.edu>", the ni_pcimio module
is missing module metadata, including a license.
This patch adds module metadata to all the NI comedi driver modules. It
also removes a duplicate MODULE_LICENSE("GPL") line from the "mite"
module.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: W. Trevor King <wking@drexel.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
OMAP2 (armv6) and MX3 turn off support for the V6K instructions, which
when they include support for SMP kernels means that the resulting
kernel is unsafe on SMP and can result in corrupted filesystems as we
end up using unsafe bitops.
Re-enable the use of V6K instructions on such kernels, and let such
kernels running on V6 CPUs eat undefined instruction faults which will
be much safer than filesystem corruption. Next merge window we can fix
this properly (as it requires a much bigger set of changes.)
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The gs_index loading code uses the swapgs instruction to
switch to the user gs_base temporarily. This is unsave in an
lightweight exit-path in KVM on AMD because the
KERNEL_GS_BASE MSR is switches lazily. An NMI happening in
the critical path of load_gs_index may use the wrong GS_BASE
value then leading to unpredictable behavior, e.g. a
triple-fault.
This patch fixes the issue by making sure that load_gs_index
is called only with a valid KERNEL_GS_BASE value loaded in
KVM.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
The use of wrong SD detect pin was introduced by this commit:
ARM: pxa: Push Colibri evalboard MFP into module files
This fixes it.
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
Since mfpr_mmio_base[0] is not always valid on later SoCs,
fixed mpfr_sync() to read back from valid mfp offset always.
Signed-off-by: Yu Tang <ytang5@marvell.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
Commit 93aae17af1 ("sr: implement
sr_check_events()") replaced the media_changed op with the
check_events op in drivers/scsi/sr.c
All users that check for the CDC_MEDIA_CHANGED capbility try both
the check_events op and the media_changed op, but register_cdrom()
was requiring media_changed.
This patch fixes the capability checking.
The cdrom_select_disc ioctl is also using the two operations, so
they should be required for CDC_SELECT_DISC too.
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Cc: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Commit 7667aa0630 added logic to wait for
the last queue of the group to become busy (have at least one request),
so that the group does not lose out for not being continuously
backlogged. The commit did not check for the condition that the last
queue already has some requests. As a result, if the queue already has
requests, wait_busy is set. Later on, cfq_select_queue() checks the
flag, and decides that since the queue has a request now and wait_busy
is set, the queue is expired. This results in early expiration of the
queue.
This patch fixes the problem by adding a check to see if queue already
has requests. If it does, wait_busy is not set. As a result, time slices
do not expire early.
The queues with more than one request are usually buffered writers.
Testing shows improvement in isolation between buffered writers.
Cc: stable@kernel.org
Signed-off-by: Justin TerAvest <teravest@google.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The TCP tracking code has a special case that allows to return
NF_REPEAT if we receive a new SYN packet while in TIME_WAIT state.
In this situation, the TCP tracking code destroys the existing
conntrack to start a new clean session.
[DESTROY] tcp 6 src=192.168.0.2 dst=192.168.1.2 sport=38925 dport=8000 src=192.168.1.2 dst=192.168.1.100 sport=8000 dport=38925 [ASSURED]
[NEW] tcp 6 120 SYN_SENT src=192.168.0.2 dst=192.168.1.2 sport=38925 dport=8000 [UNREPLIED] src=192.168.1.2 dst=192.168.1.100 sport=8000 dport=38925
However, this is a problem for the iptables' CT target event filtering
which will not work in this case since the conntrack template will not
be there for the new session. To fix this, we reassign the conntrack
template to the packet if we return NF_REPEAT.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Currently, in case reload pch_can,
pch_can not to be able to catch interrupt.
The cause is bus-master is not set in pch_can.
Thus, add enabling bus-master processing.
Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, when rmmod pch_can, kernel failure occurs.
The cause is pci_iounmap executed before pch_can_reset.
Thus pci_iounmap moves after pch_can_reset.
Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, 800k comms fails since prop_seg set zero.
(EG20T PCH CAN register of prop_seg must be set more than 1)
To prevent prop_seg set to zero, change tseg2_min 1 to 2.
Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In order to determine whether an SMBEcho request can be sent
we need to know that the socket is established (server tcpStatus == CifsGood)
AND that an SMB NegotiateProtocol has been sent (server maxBuf != 0).
Without the second check we can send an Echo request during reconnection
before the server can accept it.
CC: JG <jg@cms.ac>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
In commit aa94210411 ("net: init ingress
queue") we moved the allocation and lock initialization of the queues
into alloc_netdev_mq() since register_netdevice() is way too late.
The problem is that dev->type is not setup until the setup()
callback is invoked by alloc_netdev_mq(), and the dev->type is
what determines the lockdep class to use for the locks in the
queues.
Fix this by doing the queue allocation after the setup() callback
runs.
This is safe because the setup() callback is not allowed to make any
state changes that need to be undone on error (memory allocations,
etc.). It may, however, make state changes that are undone by
free_netdev() (such as netif_napi_add(), which is done by the
ipoib driver's setup routine).
The previous code also leaked a reference to the &init_net namespace
object on RX/TX queue allocation failures.
Signed-off-by: David S. Miller <davem@davemloft.net>
rtnl_link_ops->setup(), and the "setup" callback passed to alloc_netdev*(),
cannot make state changes which need to be undone on failure. There is
no cleanup mechanism available at this point.
So we have to add the caif private instance to the global list once we
are sure that register_netdev() has succedded in ->newlink().
Otherwise, if register_netdev() fails, the caller will invoke free_netdev()
and we will have a reference to freed up memory on the chnl_net_list.
Signed-off-by: David S. Miller <davem@davemloft.net>
Specification links:
- CDC NCM errata link:
http://www.usb.org/developers/devclass_docs/NCM10_012011.zip
- CDC and WMC errata link:
http://www.usb.org/developers/devclass_docs/CDC1.2_WMC1.1_012011.zip
Changes:
- driver updated to match cdc.h header with errata changes
- added support for USB_CDC_SET_NTB_INPUT_SIZE control request with
8 byte length
- fixes to comply with specification: send only control requests supported by
device, set number of datagrams for IN direction, connection speed structure
update, etc.
- packet loss fixed for tx direction; misleading flag renamed.
- adjusted hard_mtu value.
Signed-off-by: Alexey Orishko <alexey.orishko@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The outvq needs to be woken up on host notifications so that buffers
consumed by the host can be reclaimed, outvq freed, and application
writes may proceed again.
The need for this is now finally noticed when I have qemu patches ready
to use nonblocking IO and flow control.
CC: Hans de Goede <hdegoede@redhat.com>
CC: stable@kernel.org
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Hans de Goede <hdegoede@redhat.com>
The commit 53d7d69d8f
ALSA: hdmi - support infoframe for DisplayPort
dropped the initialization of CA field accidentally.
This resulted in only two-channel LPCM mode on Nvidia machines.
Reference: kernel bug 28592
https://bugzilla.kernel.org/show_bug.cgi?id=28592
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: <stable@kernel.org>
Tim Deegan