readahead: make context readahead more conservative

This helps performance on moderately dense random reads on SSD.

Transaction-Per-Second numbers provided by Taobao:

		QPS	case
		-------------------------------------------------------
		7536	disable context readahead totally
w/ patch:	7129	slower size rampup and start RA on the 3rd read
		6717	slower size rampup
w/o patch:	5581	unmodified context readahead

Before, readahead will be started whenever reading page N+1 when it happen
to read N recently.  After patch, we'll only start readahead when *three*
random reads happen to access pages N, N+1, N+2.  The probability of this
happening is extremely low for pure random reads, unless they are very
dense, which actually deserves some readahead.

Also start with a smaller readahead window.  The impact to interleaved
sequential reads should be small, because for a long run stream, the the
small readahead window rampup phase is negletable.

The context readahead actually benefits clustered random reads on HDD
whose seek cost is pretty high.  However as SSD is increasingly used for
random read workloads it's better for the context readahead to concentrate
on interleaved sequential reads.

Another SSD rand read test from Miao

        # file size:        2GB
        # read IO amount: 625MB
        sysbench --test=fileio          \
                --max-requests=10000    \
                --num-threads=1         \
                --file-num=1            \
                --file-block-size=64K   \
                --file-test-mode=rndrd  \
                --file-fsync-freq=0     \
                --file-fsync-end=off    run

shows the performance of btrfs grows up from 69MB/s to 121MB/s, ext4 from
104MB/s to 121MB/s.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Tested-by: Tao Ma <tm@tao.ma>
Tested-by: Miao Xie <miaox@cn.fujitsu.com>
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>
msm-sleeper: limit max freq when screen is off

Signed-off-by: flar2 <asegaert@gmail.com>
msm-sleeper: disable messages

Signed-off-by: flar2 <asegaert@gmail.com>
msm-sleeper: add ex_max_freq interface

Signed-off-by: flar2 <asegaert@gmail.com>
Adjust some voltages

Signed-off-by: flar2 <asegaert@gmail.com>
PM: devfreq: Fix simple_ondemand crashing on startup

simple_ondemands private data must be set to NULL, otherwise we would
run into a NULL pointer in kgsl_devfreq_get_dev_status().

Change-Id: I6cc6a8b11e3b58b8c3e3c26d43ee36949cf62351

Signed-off-by: flar2 <asegaert@gmail.com>
ASoC: wcd9xxx: Enable headset in high performance

Invoke class AB mode for headset path when sample rate
is set to 192KHz and bit width is set to 24. Change enables
headset path in Ultra High Quality Audio(UHQA)mode.

Signed-off-by: Sudheer Papothi <spapothi@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Signed-off-by: flar2 <asegaert@gmail.com>
LCD_KCAL Colour Control for m8

Signed-off-by: flar2 <asegaert@gmail.com>
backlight_dimmer: give two dimmer options and create sysfs node

Signed-off-by: flar2 <asegaert@gmail.com>
clean up a ton of logspam

* There is so much shit in here that just constantly outputs to
  the kernel log. Set to debug because its mostly useless.

Change-Id: I1c5a021e42e0abb65bfd0549194fa97cd9fbcf4f

Signed-off-by: flar2 <asegaert@gmail.com>