Revert "msm_fb: Set backlight during resume after first display commit"

* Stick with Samsung implementation from MB1 source

This reverts commit 0d3c1687223406177c6974e5c3d7a5f0e5ecefc0.
Revert "msm_fb: changes from samsung MB1 source"

This reverts commit 217e89822f565c57877fc85797cf4705c2d86b65.
msm_fb: Set backlight during resume after first display commit

Set the backlight after resume only after the first display
commit is done. This will avoid panel specific transients to
show up on the panel during its initialization. Also, avoid
backlight scaling during resume until backlight is set.

CRs-fixed: 468633
Change-Id: Ic9e24e9cd9d57fbdd767f9dae92f418b0b139c94
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>
hrtimer: Consider preemption when migrating hrtimer cpu_bases

When switching to a new cpu_base in switch_hrtimer_base(), we
briefly enable preemption by unlocking the cpu_base lock in two
places. During this interval it's possible for the running thread
to be swapped to a different CPU.

Consider the following example:

CPU #0                                 CPU #1
----                                   ----
hrtimer_start()                        ...
 lock_hrtimer_base()
 switch_hrtimer_base()
  this_cpu = 0;
  target_cpu_base = 0;
  raw_spin_unlock(&cpu_base->lock)
<migrate to CPU 1>
...                                    this_cpu == 0
                                       cpu == this_cpu
                                       timer->base = CPU #0
                                       timer->base != LOCAL_CPU

Since the cached this_cpu is no longer accurate, we'll skip the
hrtimer_check_target() check. Once we eventually go to program
the hardware, we'll decide not to do so since it knows the real
CPU that we're running on is not the same as the chosen base. As
a consequence, we may end up missing the hrtimer's deadline.

Fix this by updating the local CPU number each time we retake a
cpu_base lock in switch_hrtimer_base().

Another possibility is to disable preemption across the whole of
switch_hrtimer_base.  This looks suboptimal since preemption
would be disabled while waiting for lock(s).

Change-Id: I3f76d528ab2288ef5f950f4d048e7f3fa6cf1228
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
hrtimer: Prevent enqueue of hrtimer on dead CPU

When switching the hrtimer cpu_base, we briefly allow for
preemption to become enabled by unlocking the cpu_base lock.
During this time, the CPU corresponding to the new cpu_base
that was selected may in fact go offline. In this scenario, the
hrtimer is enqueued to a CPU that's not online, and therefore
it never fires.

As an example, consider this example:

CPU #0                          CPU #1
----                            ----
...                             hrtimer_start()
                                 lock_hrtimer_base()
                                 switch_hrtimer_base()
                                  cpu = hrtimer_get_target() -> 1
                                  spin_unlock(&cpu_base->lock)
                                <migrate thread to CPU #0>
                                <offline>
spin_lock(&new_base->lock)
this_cpu = 0
cpu != this_cpu
enqueue_hrtimer(cpu_base #1)

To prevent this scenario, verify that the CPU corresponding to
the new cpu_base is indeed online before selecting it in
hrtimer_switch_base(). If it's not online, fallback to using the
base of the current CPU.

Change-Id: I6359cb299ba7e08abf25d3360fcdd925b4c03b69
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>