linux/Documentation
Peter Rosin 1ffcfaf195 iio: imu: inv_mpu6050: change the i2c gate to be mux-locked
The root i2c adapter lock is then no longer held by the i2c mux during
accesses behind the i2c gate, and such accesses need to take that lock
just like any other ordinary i2c accesses do.

So, declare the i2c gate mux-locked, and zap the code that makes the
unlocked i2c accesses and just use ordinary regmap_write accesses.

This also happens to fix the deadlock described in
http://patchwork.ozlabs.org/patch/584776/ authored by
Adriana Reus <adriana.reus@intel.com> and submitted by
Daniel Baluta <daniel.baluta@intel.com>

----------8<----------
iio: imu: inv_mpu6050: Fix deadlock between i2c adapter lock and mpu lock

This deadlock occurs if the accel/gyro and the sensor on the auxiliary
I2C (in my setup it's an ak8975) are working at the same time.

Scenario:

      T1					T2
     ====				       ====
inv_mpu6050_read_fifo                  aux sensor op (eg. ak8975_read_raw)
        |                                     |
mutex_lock(&indio_dev->mlock)           i2c_transfer
        |                                     |
i2c transaction                         i2c adapter lock
        |                                     |
i2c adapter lock                        i2c_mux_master_xfer
                                              |
                                        inv_mpu6050_select_bypass
                                              |
                                        mutex_lock(&indio_dev->mlock)

When we operate on an mpu sensor the order of locking is mpu lock
followed by the i2c adapter lock. However, when we operate the auxiliary
sensor the order of locking is the other way around.

...
----------8<----------

The reason this patch fixes the deadlock is that T2 does not grab the
i2c adapter lock until the very end (and grabs the newfangled i2c mux
lock where it previously grabbed the i2c adapter lock).

Acked-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Daniel Baluta <daniel.baluta@intel.com>
Tested-by: Crestez Dan Leonard <leonard.crestez@intel.com>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2016-05-04 22:39:30 +02:00
..
ABI i2c: mux: demux-pinctrl: Update docs to new sysfs-attributes 2016-04-07 21:13:02 +02:00
accounting
acpi
aoe
arm ARM: SoC 64-bit changes for v4.6 2016-03-20 15:08:45 -07:00
arm64 arm64: Add workaround for Cavium erratum 27456 2016-02-26 15:14:27 +00:00
auxdisplay
backlight
blackfin
block A relatively boring cycle in the docs tree. There's a few kernel-doc 2016-01-17 11:55:07 -08:00
blockdev cpqarray: remove it from the kernel 2016-03-14 09:06:01 -06:00
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cgroup-v1 Merge branch 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-03-18 20:25:49 -07:00
cma
connector
console
cpu-freq Documentation: cpufreq: intel_pstate: fix typo 2016-02-18 20:31:53 +01:00
cpuidle
cris
crypto crypto: doc - Use ahash 2016-02-06 15:33:11 +08:00
development-process
device-mapper dm cache: make the 'mq' policy an alias for 'smq' 2016-03-10 17:12:08 -05:00
devicetree i2c: octeon: Add support for cn78xx chips 2016-04-25 23:49:41 +02:00
dmaengine
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features arm64 updates for 4.6: 2016-03-17 20:03:47 -07:00
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gpio gpio: documenatation: fix GPIO_LOOKUP{,_IDX} documentation 2016-02-25 16:01:51 +01:00
hid
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i2c iio: imu: inv_mpu6050: change the i2c gate to be mux-locked 2016-05-04 22:39:30 +02:00
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infiniband staging/rdma/hfi1: Method to toggle "fast ECN" detection 2016-03-10 20:37:50 -05:00
input
ioctl gpio: uapi: use 0xB4 as ioctl() major 2016-03-10 16:02:52 +07:00
isdn isdn: i4l: move active-isdn drivers to staging 2016-03-05 15:00:38 -08:00
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power PM / runtime: Document steps for device removal 2016-04-05 03:46:59 +02:00
powerpc cxl: Support to flash a new image on the adapter from a guest 2016-03-09 23:39:56 +11:00
pps
prctl Documentation: Fix int/unsigned int comparison 2016-02-17 14:09:43 -07:00
pti
ptp Another relatively boring cycle for the docs tree: typo fixes, translation 2016-03-17 12:09:35 -07:00
rapidio rapidio: add mport char device driver 2016-03-22 15:36:02 -07:00
RCU
s390
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scsi st: Fix MTMKPART to work with newer drives 2016-02-23 21:27:02 -05:00
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serial tty: Remove chars_in_buffer() line discipline method 2016-01-27 15:01:44 -08:00
sh
sound Merge branch 'topic/hda-mst' into for-next 2016-02-10 09:25:15 +01:00
spi
sysctl Merge branch 'akpm' (patches from Andrew) 2016-03-18 19:26:54 -07:00
target target/user: Report capability of handling out-of-order completions to userspace 2016-03-10 21:49:09 -08:00
thermal thermal: doc: Add details of devm_thermal_zone_of_sensor_{register,unregister} 2016-03-09 10:51:41 -08:00
timers Another relatively boring cycle for the docs tree: typo fixes, translation 2016-03-17 12:09:35 -07:00
tpm
trace
usb usb: devio: Add ioctl to disallow detaching kernel USB drivers. 2016-03-05 12:05:01 -08:00
vDSO
video4linux [media] saa7134: Add support for Snazio TvPVR PRO 2016-03-03 09:03:48 -03:00
virtual One of the largest releases for KVM... Hardly any generic improvement, 2016-03-16 09:55:35 -07:00
vm mm: thp: set THP defrag by default to madvise and add a stall-free defrag option 2016-03-17 15:09:34 -07:00
w1
watchdog Merge git://www.linux-watchdog.org/linux-watchdog 2016-03-19 19:35:51 -07:00
wimax
x86 x86/Documentation: Start documenting x86 topology 2016-03-29 10:45:04 +02:00
xtensa
zh_CN Documentation: Chinese translation of arm64/silicon-errata.txt 2016-02-17 14:08:07 -07:00
00-INDEX
adding-syscalls.txt
applying-patches.txt
assoc_array.txt
atomic_ops.txt
bad_memory.txt
basic_profiling.txt
bcache.txt
binfmt_misc.txt
braille-console.txt
bt8xxgpio.txt
btmrvl.txt
BUG-HUNTING
bus-virt-phys-mapping.txt
cachetlb.txt
cgroup-v2.txt Merge branch 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-03-21 10:05:13 -07:00
Changes
circular-buffers.txt
clk.txt
coccinelle.txt
CodeOfConflict
CodingStyle Documentation/CodingStyle: add space before parenthesis in example macro 2016-01-25 12:36:28 -07:00
cpu-hotplug.txt
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt
devices.txt
digsig.txt
DMA-API-HOWTO.txt dma-mapping: always provide the dma_map_ops based implementation 2016-01-20 17:09:18 -08:00
DMA-API.txt
DMA-attributes.txt ARM: 8506/1: common: DMA-mapping: add DMA_ATTR_ALLOC_SINGLE_PAGES attribute 2016-02-11 15:33:38 +00:00
dma-buf-sharing.txt dma-buf: Update docs for SYNC ioctl 2016-03-21 09:26:45 +01:00
DMA-ISA-LPC.txt
dontdiff
dynamic-debug-howto.txt
edac.txt
efi-stub.txt
eisa.txt
email-clients.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcov.txt
gdb-kernel-debugging.txt
highuid.txt
HOWTO Documentation: Howto: Fixed subtitles style 2016-03-09 15:30:03 -07:00
hsi.txt
hw_random.txt
hwspinlock.txt
init.txt
initrd.txt
intel_txt.txt
Intel-IOMMU.txt iommu/vt-d: Fix link to Intel IOMMU Specification 2016-01-29 12:32:12 +01:00
io_ordering.txt
io-mapping.txt
iostats.txt
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt
IRQ.txt
irqflags-tracing.txt
isapnp.txt
java.txt
kasan.txt mm, kasan: SLAB support 2016-03-25 16:37:42 -07:00
kcov.txt kernel: add kcov code coverage 2016-03-22 15:36:02 -07:00
kernel-doc-nano-HOWTO.txt
kernel-docs.txt
kernel-parameters.txt Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
kernel-per-CPU-kthreads.txt
kmemcheck.txt
kmemleak.txt
kobject.txt
kprobes.txt
kref.txt
kselftest.txt Documentation: kselftest: Remove duplicate word 2016-03-09 15:33:38 -07:00
ldm.txt
local_ops.txt
lockup-watchdogs.txt
logo.gif
logo.txt
lzo.txt
magic-number.txt
mailbox.txt
Makefile
ManagementStyle
md-cluster.txt
md.txt
memory-barriers.txt documentation: Clarify compiler store-fusion example 2016-03-14 15:52:19 -07:00
memory-hotplug.txt memory-hotplug: add automatic onlining policy for the newly added memory 2016-03-15 16:55:16 -07:00
men-chameleon-bus.txt
module-signing.txt modsign: Fix documentation on module signing enforcement parameter. 2016-03-12 01:48:11 -07:00
mono.txt
nommu-mmap.txt
ntb.txt
numastat.txt
oops-tracing.txt
padata.txt
parport-lowlevel.txt
parport.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt
pinctrl.txt
pnp.txt
preempt-locking.txt
printk-formats.txt mm, printk: introduce new format string for flags 2016-03-15 16:55:16 -07:00
pwm.txt
ramoops.txt
rbtree.txt
remoteproc.txt
rfkill.txt rfkill: Add documentation about LED triggers 2016-02-24 09:13:12 +01:00
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt rtc: implement a sysfs interface for clock offset 2016-03-14 17:08:16 +01:00
SAK.txt
SecurityBugs
serial-console.txt
sgi-ioc4.txt
SM501.txt
smsc_ece1099.txt
sparse.txt
stable_api_nonsense.txt
stable_kernel_rules.txt
static-keys.txt
SubmitChecklist
SubmittingDrivers
SubmittingPatches SubmittingPatches: fix spelling of "git send-email" 2016-01-25 12:30:18 -07:00
svga.txt
sysfs-rules.txt
sysrq.txt
this_cpu_ops.txt
ubsan.txt UBSAN: run-time undefined behavior sanity checker 2016-01-20 17:09:18 -08:00
unaligned-memory-access.txt
unicode.txt
unshare.txt
vfio.txt
VGA-softcursor.txt
vgaarbiter.txt
video-output.txt
vme_api.txt
volatile-considered-harmful.txt
workqueue.txt
xillybus.txt
xz.txt
zorro.txt