Input: Send events one packet at a time

On heavy event loads, such as a multitouch driver, the irqsoff latency
can be as high as 250 us.  By accumulating a frame worth of data
before passing it on, the latency can be dramatically reduced.  As a
side effect, the special EV_SYN handling can be removed, since the
frame is now atomic.

This patch adds the events() handler callback and uses it if it
exists. The latency is improved by 50 us even without the callback.

Change-Id: Iebd9b1868ae6300a922a45b6d104e7c2b38e4cf5
Cc: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Tested-by: Ping Cheng <pingc@wacom.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

Input: Improve the events-per-packet estimate

The events-per-packet estimate has so far been used by MT devices
only. This patch adjusts the packet buffer size to also accomodate the
KEY and MSC events.  Keyboards normally send one or two keys at a
time. MT devices normally send a number of button keys along with the
MT information.  The buffer size chosen here covers those cases, and
matches the default buffer size in evdev. Since the input estimate is
now preferred, remove the special input-mt estimate.

Reviewed-and-tested-by: Ping Cheng <pingc@wacom.com>
Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: flar2 <asegaert@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

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: flar2 <asegaert@gmail.com>
Max Readahead to 1024 kB.

* This values was optimal from my testing.

Signed-off-by: Chester Kener <Cl3Kener@gmail.com>
mach-msm: Add msm_mpdecision Kconfig & Makefile hooks
Also rename qcom's mpdecision to stay in place and be used if CONFIG_MSM_MPDEC is not set

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>

Conflicts:
	arch/arm/mach-msm/Makefile
mach-msm: Add msm_mpdecision
This currently only does the following thing:
Screen on -> CPU1 online
Screen off -> CPU1 offline

More to come.

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
mach-msm: mpdecision: small cleanup

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: add load based decision making

This now works like the mpdecision binary from QCOM.
CPU hotplugging/unplugging based on system load.

A sysfs interface will be built in with a later commit.

Signed-off-by: showp1984 <showp1984@gmail.com>

Conflicts:
	arch/arm/mach-msm/msm_rq_stats.c
mach-msm: mpdecision: restructure locks, add delay

The new delay allows the CPU to come up before any other action is taken.
This prevents fast plugging and also ensures the CPU hotplug process
is really done, before trying to unplug it again (or plug it).

The new locks are more efficient, and only used if necessary.

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: pause if CPU is unplugged outside of mpdecision

This fixes cpu wars if something else tries to control the cpus.
default delay: 10000ms

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: change early_suspend_level to blank_screen

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: don't start immediately

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: show cpumask after up/down

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: always set the suspend var

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: remove up/down delay, our default delay is large enough

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: add email to (c)

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: fix foreign hotplug/unplug detection

Signed-off-by: showp1984 <showp1984@gmail.com>

Conflicts:

	arch/arm/mach-msm/msm_mpdecision.c
mach-msm: mpdecision: show how long the cpu was online

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: rename msm_mpdec_suspend to msm_mpdec_cpudata

Since this is being used for more than suspend stuff the old name
just isn't accurate anymore.

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: add sysfs interface

Signed-off-by: showp1984 <showp1984@gmail.com>
mach-msm: mpdecision: remove debug output

Signed-off-by: showp1984 <showp1984@gmail.com>