writeback: Fix periodic writeback after fs mount

Code in blkdev.c moves a device inode to default_backing_dev_info when
the last reference to the device is put and moves the device inode back
to its bdi when the first reference is acquired. This includes moving to
wb.b_dirty list if the device inode is dirty. The code however doesn't
setup timer to wake corresponding flusher thread and while wb.b_dirty
list is non-empty __mark_inode_dirty() will not set it up either. Thus
periodic writeback is effectively disabled until a sync(2) call which
can
lead to unexpected data loss in case of crash or power failure.

Fix the problem by setting up a timer for periodic writeback in case we
add the first dirty inode to wb.b_dirty list in bdev_inode_switch_bdi().

Reported-by: Bert De Jonghe <Bert.DeJonghe@amplidata.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
update battery config
procfs: add num_to_str() to speed up /proc/stat
msm: kgsl: add Simple GPU governor.

* Original code and idea from @faux123.
 * Current commit has some custom changes:
   - added the load history buffer to filter
     spikes and average the GPU scaling.

Change-Id: Id79819a6894a4fe0b78558aef49eec0163700b91
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
lib/int_sqrt.c: optimize square root algorithm

Optimize the current version of the shift-and-subtract (hardware)
algorithm, described by John von Newmann[1] and Guy L Steele.

Iterating 1,000,000 times, perf shows for the current version:

 Performance counter stats for './sqrt-curr' (10 runs):

         27.170996 task-clock                #    0.979 CPUs utilized
         ( +-  3.19% )
                 3 context-switches          #    0.103 K/sec
         ( +-  4.76% )
                 0 cpu-migrations            #    0.004 K/sec
         ( +-100.00% )
               104 page-faults               #    0.004 M/sec
         ( +-  0.16% )
        64,921,199 cycles                    #    2.389 GHz
         ( +-  0.03% )
        28,967,789 stalled-cycles-frontend   #   44.62% frontend cycles
idle     ( +-  0.18% )
   <not supported> stalled-cycles-backend
       104,502,623 instructions              #    1.61  insns per cycle
                                             #    0.28  stalled cycles
per insn  ( +-  0.00% )
        34,088,368 branches                  # 1254.587 M/sec
         ( +-  0.00% )
             4,901 branch-misses             #    0.01% of all branches
         ( +-  1.32% )

       0.027763015 seconds time elapsed
         ( +-  3.22% )

And for the new version:

Performance counter stats for './sqrt-new' (10 runs):

          0.496869 task-clock                #    0.519 CPUs utilized
         ( +-  2.38% )
                 0 context-switches          #    0.000 K/sec
                 0 cpu-migrations            #    0.403 K/sec
         ( +-100.00% )
               104 page-faults               #    0.209 M/sec
         ( +-  0.15% )
           590,760 cycles                    #    1.189 GHz
         ( +-  2.35% )
           395,053 stalled-cycles-frontend   #   66.87% frontend cycles
idle     ( +-  3.67% )
   <not supported> stalled-cycles-backend
           398,963 instructions              #    0.68  insns per cycle
                                             #    0.99  stalled cycles
per insn  ( +-  0.39% )
            70,228 branches                  #  141.341 M/sec
         ( +-  0.36% )
             3,364 branch-misses             #    4.79% of all branches
         ( +-  5.45% )

       0.000957440 seconds time elapsed
         ( +-  2.42% )

Furthermore, this saves space in instruction text:

   text    data     bss     dec     hex filename
    111       0       0     111      6f lib/int_sqrt-baseline.o
     89       0       0      89      59 lib/int_sqrt.o

[1] http://en.wikipedia.org/wiki/First_Draft_of_a_Report_on_the_EDVAC

Change-Id: I1a4970a9ea5cfdc1cd3e199d8f3af5ce874cba3d
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Reviewed-by: Jonathan Gonzalez <jgonzlez@linets.cl>
Tested-by: Jonathan Gonzalez <jgonzlez@linets.cl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
update touchscreen power
driver: pmem: add PMEM_FLUSH
arm: Enable ARM_HAS_SG_CHAIN
kgsl: Fix GPU freq being set to the max by default
USB OTG
Disable debugfs